From 7dfb327bb786a6f0a09595770cb821097539a330 Mon Sep 17 00:00:00 2001
From: "Fry (Paperclip)" <noreply@paperclip.ing>
Date: Sun, 27 Sep 2026 02:27:24 +0000
Subject: [PATCH] feat(instructions): persist canonical revisions with
 authorized history and restore

Implement PAP-66 foundation: exact content history, transactional compare-and-swap saves, current responsible-user authorization, recoverable materialization, and editor history. Keep run staging and cleanup integration with PAP-63.

Co-Authored-By: Paperclip <noreply@paperclip.ing>
---
 doc/DATABASE.md                               |  10 +
 doc/agent-instruction-revisions.md            | 164 ++++
 .../migrations/0285_legal_thunderbolts.sql    |  32 +
 ...{0280_snapshot.json => 0285_snapshot.json} | 903 +++++++++++++++++-
 packages/db/src/migrations/meta/_journal.json |   7 +
 .../src/schema/agent_instruction_revisions.ts |  84 ++
 packages/db/src/schema/index.ts               |   2 +
 packages/shared/src/index.ts                  |   3 +
 packages/shared/src/types/agent.ts            |  60 ++
 packages/shared/src/types/index.ts            |   2 +
 packages/shared/src/validators/agent.ts       |  13 +-
 packages/shared/src/validators/index.ts       |   2 +
 .../agent-instruction-revisions.test.ts       | 240 +++++
 .../agent-instructions-routes.test.ts         |  79 +-
 .../agent-instructions-service.test.ts        |  16 +-
 .../__tests__/built-in-agent-routes.test.ts   |   2 +-
 server/src/__tests__/built-in-agents.test.ts  |  36 +-
 server/src/routes/agents.ts                   |  95 +-
 server/src/routes/built-in-agents.ts          |   2 +-
 server/src/routes/openapi.ts                  |  14 +
 .../agent-instruction-authorization.ts        | 175 ++++
 .../src/services/agent-instruction-files.ts   | 149 +++
 .../services/agent-instruction-revisions.ts   | 469 +++++++++
 server/src/services/agent-instructions.ts     | 129 ++-
 server/src/services/authorization.ts          |  21 +-
 server/src/services/built-in-agents.ts        |  59 +-
 server/src/services/change-consent-gate.ts    |   2 +-
 server/src/services/company-portability.ts    |   2 +-
 server/src/services/plugin-managed-agents.ts  |   2 +-
 ui/src/api/agents.ts                          |  13 +-
 ui/src/components/InstructionHistory.tsx      | 145 +++
 .../pages/AgentDetail.instructions.test.tsx   |  35 +
 ui/src/pages/AgentDetail.tsx                  |  40 +-
 33 files changed, 2892 insertions(+), 115 deletions(-)
 create mode 100644 doc/agent-instruction-revisions.md
 create mode 100644 packages/db/src/migrations/0285_legal_thunderbolts.sql
 rename packages/db/src/migrations/meta/{0280_snapshot.json => 0285_snapshot.json} (98%)
 create mode 100644 packages/db/src/schema/agent_instruction_revisions.ts
 create mode 100644 server/src/__tests__/agent-instruction-revisions.test.ts
 create mode 100644 server/src/services/agent-instruction-authorization.ts
 create mode 100644 server/src/services/agent-instruction-files.ts
 create mode 100644 server/src/services/agent-instruction-revisions.ts
 create mode 100644 ui/src/components/InstructionHistory.tsx

diff --git a/doc/DATABASE.md b/doc/DATABASE.md
index 1d21aa87f81..48321923a79 100644
--- a/doc/DATABASE.md
+++ b/doc/DATABASE.md
@@ -432,3 +432,13 @@ cleanup authority; it does not prove that remote inference has stopped. Recovery
 revokes the previous boot identity with a conditional update. Its own claim also
 expires so another sweep can finish cleanup after a restart. Historical rows keep
 null ownership fields and follow the previous recovery path.
+
+## Agent instruction content revisions
+
+`agent_instruction_revisions` stores immutable exact UTF-8 content and server-bound
+attribution. `agent_instruction_heads` selects the current revision by company,
+agent, and configured entry filename. Revision/head/activity changes share one
+transaction; disk content is a recoverable projection. Existing managed files
+are seeded lazily without rewriting their content. See
+[Canonical agent instruction revisions](agent-instruction-revisions.md) for the
+commit, conflict, authorization, and runtime integration contract.
diff --git a/doc/agent-instruction-revisions.md b/doc/agent-instruction-revisions.md
new file mode 100644
index 00000000000..126ce8727cf
--- /dev/null
+++ b/doc/agent-instruction-revisions.md
@@ -0,0 +1,164 @@
+# Canonical agent instruction revisions
+
+Managed entry content has one database history. `agent_instruction_revisions`
+stores exact UTF-8 bytes as base64 text (including BOM, CRLF, trailing whitespace,
+and NUL), SHA-256, byte length, parent/base revision, restore origin, actor,
+responsible user, source run, source, and creation time. `agent_instruction_heads`
+selects one revision per company, agent, and relative entry filename. Composite
+foreign keys bind heads to their owner's content and agents to their company.
+Configuration snapshots in `agent_config_revisions` are not content history.
+Migration 0285 adds the tables; existing managed files are seeded lazily on the
+first authorized canonical read or commit, without changing their bytes.
+
+The configured `instructionsEntryFile` is authoritative. Legacy managed
+`instructionsFilePath` can select a nested filename. A missing configured entry
+never causes a scan to select some other AGENTS.md. Supporting bundle files keep
+the existing file API; only the configured entry participates in this history.
+
+## Service integration
+
+Import `agentInstructionRevisionService` from
+`server/src/services/agent-instruction-revisions.ts` and instantiate it with `db`.
+Use the server's authenticated actor, never an actor or responsible-user ID from
+request/tool arguments. `AuthorizationActor` is an internal server type.
+
+```ts
+const revisions = agentInstructionRevisionService(db);
+const target = { companyId, agentId: targetAgentId };
+const baseline = await revisions.readCurrent(target, serverActor);
+// null means no committed head and no existing managed entry.
+// For an existing head, retain its entryFile/id/hash in the server-owned mapping.
+const receipt = await revisions.commit({
+  ...target,
+  entryFile: baseline!.revision.entryFile,
+  baseRevisionId: baseline!.revision.id,
+  content: collectedBytes, // string or Uint8Array, at most 1 MiB of valid UTF-8
+  source: "cleanup",      // board | api | tool | cleanup
+}, serverActor);
+```
+
+For new entries, obtain the configured entry from `deriveBundleState(agent)` and
+pass `baseRevisionId: null`. Do not turn a conflict into a null base or silently
+retry with the latest head. `readInstructionBytes(root, entryFile)` from
+`agent-instruction-files.ts` validates a specifically registered file; it returns
+null for a missing file, rejects symlinks in the path, rejects special files, and
+bounds the read itself. The collector must distinguish a missing working file
+from a valid empty file and must stop the process before collecting it.
+
+Public operations:
+
+- `readCurrent(target, actor)` returns `AgentInstructionSnapshot | null` and seeds
+  existing managed bytes. Reads do not require content-edit permission.
+- `commit(input, actor)` returns `AgentInstructionCommitReceipt`.
+- `history({ ...target, entryFile, cursor?, limit? }, actor)` returns metadata and
+  `nextCursor`; pages are capped at 100 revisions (default 50).
+- `readRevision({ ...target, entryFile, revisionId }, actor)` returns exact content.
+- `diff({ ...target, entryFile, fromRevisionId, toRevisionId }, actor)` returns both
+  snapshots and an exact common-prefix/replacement/common-suffix diff in linear
+  time. It does not attempt an automatic merge.
+- `restore({ ...target, entryFile, revisionId, baseRevisionId }, actor)` uses the
+  same authorization and CAS path. It appends a revision with source `restore`
+  and `restoredFromRevisionId`. Identical content is a no-op.
+- `materializeCurrent(target)` is an **internal recovery operation**, not an
+  authorization API. It copies only the current committed head to the managed
+  path while holding the agent lock. Call before launching a run that reads disk
+  and after restarting following an interrupted materialization.
+
+A transaction locks the target agent, rechecks current authority, inserts a
+revision, moves the head, and inserts its activity record. A different current
+head yields 409. Identical content returns the existing receipt without another
+revision, including retries whose base has advanced to that same content.
+Materialization happens after commit under the same serialization lock, always
+from the latest head. It uses a temporary file and atomic rename. A later save
+cannot be overwritten by an older materializer. A crash or disk error leaves the
+database head recoverable. A receipt with `materialization: "pending"` means the
+revision is durable and the disk copy still needs repair; it does not mean the
+commit failed. GET bundle also attempts that repair and displays a warning if
+repair fails. A successful materializer may have copied a newer head than the
+receipt if another commit already completed.
+
+`authorizeInstructionCommit(connection, actor, target)` and
+`resolveInstructionActor(connection, actor)` are exported from
+`agent-instruction-authorization.ts`. The commit service calls them itself;
+callers must not treat an earlier authorization result as a reusable grant.
+Agent callers must supply the server-bound agent/company plus registered run or
+active API key. The service reloads responsible identity, accepted active run
+identity context, key scope/revocation, user existence, active company membership,
+current target edit permission, and agent restrictions. When capturing a baseline,
+retain the server-resolved `onBehalfOfUserId` so identity changes before cleanup
+fail closed instead of attributing the candidate to a different user.
+
+Ordinary standard agents inherit their responsible user's existing target
+`agents:configure` access for content only. They do not need their own blanket
+agent-admin grant. An explicit scoped configure grant or suggest-only grant still
+constrains them; suggest-only mutation consumes the existing accepted-change
+confirmation inside the commit transaction. Low-trust, task-bridge, and skill-test
+containment remains enforced. This path enforces the responsible-user ceiling even
+if the general responsible-user policy is configured in shadow mode.
+
+## HTTP and editor
+
+Existing company-scoped agent URLs now support:
+
+| Operation | Route |
+| --- | --- |
+| Current entry and revision metadata | `GET /api/agents/:id/instructions-bundle/file?path=...` |
+| Content save | `PUT /api/agents/:id/instructions-bundle/file` |
+| History | `GET /api/agents/:id/instructions-bundle/history?path=...&cursor=...` |
+| Revision content | `GET /api/agents/:id/instructions-bundle/revision/:revisionId?path=...` |
+| Diff | `GET /api/agents/:id/instructions-bundle/diff?path=...&from=...&to=...` |
+| Restore | `POST /api/agents/:id/instructions-bundle/restore` |
+
+Entry PUT requires `{ path, content, baseRevisionId }`. Restore requires
+`{ path, revisionId, baseRevisionId }`. Content requests reject unknown fields,
+including supplied responsible identity. Save/restore return the normal file
+detail plus `revision` and `receipt`. The existing editor pins a draft's base,
+retains edits on conflicts, shows history and exact revision content/differences,
+and restores against the currently displayed head. Save or discard local edits
+before restoring. Configuration changes (root, entry selection, legacy prompt
+removal) retain the configuration permission gate.
+
+`AgentInstructionSnapshot`, `AgentInstructionRevision`,
+`AgentInstructionCommitReceipt`, `AgentInstructionHistory`,
+`AgentInstructionDiff`, `AgentInstructionErrorCode`, and
+`AgentInstructionErrorDetails` are exported from `@paperclipai/shared`.
+Errors use `HttpError` and the existing HTTP error envelope. A conflict may
+return a null `currentRevisionId` when the existing disk file has not yet been
+seeded; read the current entry to obtain its durable initial revision:
+
+| Status | Detail code / action |
+| --- | --- |
+| 409 | `INSTRUCTION_REVISION_CONFLICT`: preserve candidate, read current head, explicitly resolve |
+| 409 | `INSTRUCTION_ENTRY_CHANGED`: configured entry changed; do not collect into the replacement entry |
+| 403 | `INSTRUCTION_IDENTITY_INVALID`, `RESPONSIBLE_USER_UNAVAILABLE`, `RESPONSIBLE_USER_UNAUTHORIZED`, or existing authorization/consent denial |
+| 422 | `INSTRUCTION_BASE_REQUIRED`: read first and provide the base |
+| 422 | `INSTRUCTION_CONTENT_INVALID`, `INSTRUCTION_PATH_INVALID`: reject candidate; preserve canonical bytes |
+| 422 | `INSTRUCTION_MANAGED_BUNDLE_REQUIRED`: instance administrator must explicitly migrate the external bundle |
+| 422 | `INSTRUCTION_REVISION_REQUIRED`: use canonical content commit instead of filesystem overwrite |
+| 404 | Target or revision is absent from the requested owner scope |
+
+External host bundles are never automatically seeded or written by this service.
+Their existing instance-admin read/configuration restrictions remain. Managed
+bootstrap/import/reset helpers now refuse to overwrite an existing entry with
+different content or any entry with revision history. Apply content changes through
+the canonical commit path; provisioning a new entry remains supported. These
+helpers do not provide an alternate content-history bypass. Supporting-file writes
+reload configuration under the same agent lock and refuse current or historical
+versioned entries, including when a route has a stale configuration snapshot.
+Board stock resets
+for built-in agents pass the authenticated actor through the same commit service.
+Automatic reconciliation preserves existing stock content when no responsible
+operator is present; the available update remains visible for an authorized reset.
+Generic import and plugin reset callers must use the canonical writer to replace
+existing versioned content; their filesystem initialization helper fails closed.
+
+## Runtime handoff boundary
+
+This foundation does not register run-local copies, change native or legacy
+staging, dispatch runner tools, collect stopped runs, or persist pending cleanup
+candidates. Those integrations must retain the baseline and server identity,
+collect the registered private file after stop, use this commit path, preserve
+conflicts/loss evidence, and arrange bounded recovery. They must not write shared
+instruction caches or call the old filesystem `writeFile` for an entry.
+The next run should read the canonical snapshot and materialize it when disk is
+needed. Runtime cleanup parity is not established by these service/editor tests.
diff --git a/packages/db/src/migrations/0285_legal_thunderbolts.sql b/packages/db/src/migrations/0285_legal_thunderbolts.sql
new file mode 100644
index 00000000000..27522ed65a9
--- /dev/null
+++ b/packages/db/src/migrations/0285_legal_thunderbolts.sql
@@ -0,0 +1,32 @@
+CREATE TABLE "agent_instruction_heads" (
+	"company_id" uuid NOT NULL,
+	"agent_id" uuid NOT NULL,
+	"entry_file" text NOT NULL,
+	"revision_id" uuid NOT NULL,
+	"updated_at" timestamp with time zone DEFAULT now() NOT NULL,
+	CONSTRAINT "agent_instruction_heads_identity_uq" UNIQUE("company_id","agent_id","entry_file")
+);
+--> statement-breakpoint
+CREATE TABLE "agent_instruction_revisions" (
+	"id" uuid PRIMARY KEY DEFAULT gen_random_uuid() NOT NULL,
+	"company_id" uuid NOT NULL,
+	"agent_id" uuid NOT NULL,
+	"entry_file" text NOT NULL,
+	"content_base64" text NOT NULL,
+	"content_hash" text NOT NULL,
+	"byte_length" integer NOT NULL,
+	"parent_revision_id" uuid,
+	"base_revision_id" uuid,
+	"restored_from_revision_id" uuid,
+	"actor_agent_id" uuid,
+	"actor_user_id" text,
+	"responsible_user_id" text,
+	"source_run_id" uuid,
+	"source" text NOT NULL,
+	"created_at" timestamp with time zone DEFAULT now() NOT NULL,
+	CONSTRAINT "agent_instruction_revisions_identity_uq" UNIQUE("company_id","agent_id","entry_file","id")
+);
+--> statement-breakpoint
+ALTER TABLE "agent_instruction_heads" ADD CONSTRAINT "agent_instruction_heads_company_id_agent_id_entry_file_revision_id_agent_instruction_revisions_company_id_agent_id_entry_file_id_fk" FOREIGN KEY ("company_id","agent_id","entry_file","revision_id") REFERENCES "public"."agent_instruction_revisions"("company_id","agent_id","entry_file","id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+ALTER TABLE "agent_instruction_revisions" ADD CONSTRAINT "agent_instruction_revisions_company_id_agent_id_agents_company_id_id_fk" FOREIGN KEY ("company_id","agent_id") REFERENCES "public"."agents"("company_id","id") ON DELETE cascade ON UPDATE no action;--> statement-breakpoint
+CREATE INDEX "agent_instruction_revisions_history_idx" ON "agent_instruction_revisions" USING btree ("company_id","agent_id","entry_file","created_at","id");
\ No newline at end of file
diff --git a/packages/db/src/migrations/meta/0280_snapshot.json b/packages/db/src/migrations/meta/0285_snapshot.json
similarity index 98%
rename from packages/db/src/migrations/meta/0280_snapshot.json
rename to packages/db/src/migrations/meta/0285_snapshot.json
index ea3ae5e50dd..1ebca7b5290 100644
--- a/packages/db/src/migrations/meta/0280_snapshot.json
+++ b/packages/db/src/migrations/meta/0285_snapshot.json
@@ -1,6 +1,6 @@
 {
-  "id": "861a2815-1418-4c71-a77b-d0e2e9566413",
-  "prevId": "4770ad6d-2cdc-45c4-af89-c300fd134d91",
+  "id": "242cfd69-e9ef-4220-8bab-9d98d199acbe",
+  "prevId": "7db2ceec-ed62-4968-90c9-4c79206cfe34",
   "version": "7",
   "dialect": "postgresql",
   "tables": {
@@ -829,6 +829,258 @@
       "checkConstraints": {},
       "isRLSEnabled": false
     },
+    "public.agent_instruction_heads": {
+      "name": "agent_instruction_heads",
+      "schema": "",
+      "columns": {
+        "company_id": {
+          "name": "company_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "agent_id": {
+          "name": "agent_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "entry_file": {
+          "name": "entry_file",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "revision_id": {
+          "name": "revision_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "updated_at": {
+          "name": "updated_at",
+          "type": "timestamp with time zone",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {
+        "agent_instruction_heads_company_id_agent_id_entry_file_revision_id_agent_instruction_revisions_company_id_agent_id_entry_file_id_fk": {
+          "name": "agent_instruction_heads_company_id_agent_id_entry_file_revision_id_agent_instruction_revisions_company_id_agent_id_entry_file_id_fk",
+          "tableFrom": "agent_instruction_heads",
+          "tableTo": "agent_instruction_revisions",
+          "columnsFrom": [
+            "company_id",
+            "agent_id",
+            "entry_file",
+            "revision_id"
+          ],
+          "columnsTo": [
+            "company_id",
+            "agent_id",
+            "entry_file",
+            "id"
+          ],
+          "onDelete": "cascade",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {
+        "agent_instruction_heads_identity_uq": {
+          "name": "agent_instruction_heads_identity_uq",
+          "nullsNotDistinct": false,
+          "columns": [
+            "company_id",
+            "agent_id",
+            "entry_file"
+          ]
+        }
+      },
+      "policies": {},
+      "checkConstraints": {},
+      "isRLSEnabled": false
+    },
+    "public.agent_instruction_revisions": {
+      "name": "agent_instruction_revisions",
+      "schema": "",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "uuid",
+          "primaryKey": true,
+          "notNull": true,
+          "default": "gen_random_uuid()"
+        },
+        "company_id": {
+          "name": "company_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "agent_id": {
+          "name": "agent_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "entry_file": {
+          "name": "entry_file",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "content_base64": {
+          "name": "content_base64",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "content_hash": {
+          "name": "content_hash",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "byte_length": {
+          "name": "byte_length",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "parent_revision_id": {
+          "name": "parent_revision_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "base_revision_id": {
+          "name": "base_revision_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "restored_from_revision_id": {
+          "name": "restored_from_revision_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "actor_agent_id": {
+          "name": "actor_agent_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "actor_user_id": {
+          "name": "actor_user_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "responsible_user_id": {
+          "name": "responsible_user_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "source_run_id": {
+          "name": "source_run_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "source": {
+          "name": "source",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "timestamp with time zone",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        }
+      },
+      "indexes": {
+        "agent_instruction_revisions_history_idx": {
+          "name": "agent_instruction_revisions_history_idx",
+          "columns": [
+            {
+              "expression": "company_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            },
+            {
+              "expression": "agent_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            },
+            {
+              "expression": "entry_file",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            },
+            {
+              "expression": "created_at",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            },
+            {
+              "expression": "id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            }
+          ],
+          "isUnique": false,
+          "concurrently": false,
+          "method": "btree",
+          "with": {}
+        }
+      },
+      "foreignKeys": {
+        "agent_instruction_revisions_company_id_agent_id_agents_company_id_id_fk": {
+          "name": "agent_instruction_revisions_company_id_agent_id_agents_company_id_id_fk",
+          "tableFrom": "agent_instruction_revisions",
+          "tableTo": "agents",
+          "columnsFrom": [
+            "company_id",
+            "agent_id"
+          ],
+          "columnsTo": [
+            "company_id",
+            "id"
+          ],
+          "onDelete": "cascade",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {
+        "agent_instruction_revisions_identity_uq": {
+          "name": "agent_instruction_revisions_identity_uq",
+          "nullsNotDistinct": false,
+          "columns": [
+            "company_id",
+            "agent_id",
+            "entry_file",
+            "id"
+          ]
+        }
+      },
+      "policies": {},
+      "checkConstraints": {},
+      "isRLSEnabled": false
+    },
     "public.agent_memberships": {
       "name": "agent_memberships",
       "schema": "",
@@ -3302,6 +3554,13 @@
           "primaryKey": false,
           "notNull": false
         },
+        "keyboard_shortcuts": {
+          "name": "keyboard_shortcuts",
+          "type": "boolean",
+          "primaryKey": false,
+          "notNull": true,
+          "default": false
+        },
         "created_at": {
           "name": "created_at",
           "type": "timestamp with time zone",
@@ -5701,6 +5960,12 @@
           "notNull": true,
           "default": false
         },
+        "communication_guidance": {
+          "name": "communication_guidance",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
         "state": {
           "name": "state",
           "type": "text",
@@ -6611,6 +6876,13 @@
           "primaryKey": false,
           "notNull": false
         },
+        "communication_instructions": {
+          "name": "communication_instructions",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "''"
+        },
         "allow_direct_messages": {
           "name": "allow_direct_messages",
           "type": "boolean",
@@ -8096,6 +8368,519 @@
       },
       "isRLSEnabled": false
     },
+    "public.chat_github_configurations": {
+      "name": "chat_github_configurations",
+      "schema": "",
+      "columns": {
+        "endpoint_id": {
+          "name": "endpoint_id",
+          "type": "uuid",
+          "primaryKey": true,
+          "notNull": true
+        },
+        "company_id": {
+          "name": "company_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "revision": {
+          "name": "revision",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true,
+          "default": 1
+        },
+        "configuration": {
+          "name": "configuration",
+          "type": "jsonb",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "updated_by_user_id": {
+          "name": "updated_by_user_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "timestamp with time zone",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        },
+        "updated_at": {
+          "name": "updated_at",
+          "type": "timestamp with time zone",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        }
+      },
+      "indexes": {},
+      "foreignKeys": {
+        "chat_github_configurations_company_id_endpoint_id_chat_endpoints_company_id_id_fk": {
+          "name": "chat_github_configurations_company_id_endpoint_id_chat_endpoints_company_id_id_fk",
+          "tableFrom": "chat_github_configurations",
+          "tableTo": "chat_endpoints",
+          "columnsFrom": [
+            "company_id",
+            "endpoint_id"
+          ],
+          "columnsTo": [
+            "company_id",
+            "id"
+          ],
+          "onDelete": "cascade",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "policies": {},
+      "checkConstraints": {
+        "chat_github_config_revision_check": {
+          "name": "chat_github_config_revision_check",
+          "value": "\"chat_github_configurations\".\"revision\" > 0"
+        }
+      },
+      "isRLSEnabled": false
+    },
+    "public.chat_github_registrations": {
+      "name": "chat_github_registrations",
+      "schema": "",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "uuid",
+          "primaryKey": true,
+          "notNull": true,
+          "default": "gen_random_uuid()"
+        },
+        "company_id": {
+          "name": "company_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "endpoint_id": {
+          "name": "endpoint_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "user_id": {
+          "name": "user_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "state_hash": {
+          "name": "state_hash",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "trusted_origin": {
+          "name": "trusted_origin",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "status": {
+          "name": "status",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "'pending'"
+        },
+        "expires_at": {
+          "name": "expires_at",
+          "type": "timestamp with time zone",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "consumed_at": {
+          "name": "consumed_at",
+          "type": "timestamp with time zone",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "timestamp with time zone",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        }
+      },
+      "indexes": {
+        "chat_github_registration_state_uq": {
+          "name": "chat_github_registration_state_uq",
+          "columns": [
+            {
+              "expression": "state_hash",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            }
+          ],
+          "isUnique": true,
+          "concurrently": false,
+          "method": "btree",
+          "with": {}
+        },
+        "chat_github_registration_endpoint_idx": {
+          "name": "chat_github_registration_endpoint_idx",
+          "columns": [
+            {
+              "expression": "endpoint_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            },
+            {
+              "expression": "expires_at",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            }
+          ],
+          "isUnique": false,
+          "concurrently": false,
+          "method": "btree",
+          "with": {}
+        }
+      },
+      "foreignKeys": {
+        "chat_github_registrations_company_id_endpoint_id_chat_endpoints_company_id_id_fk": {
+          "name": "chat_github_registrations_company_id_endpoint_id_chat_endpoints_company_id_id_fk",
+          "tableFrom": "chat_github_registrations",
+          "tableTo": "chat_endpoints",
+          "columnsFrom": [
+            "company_id",
+            "endpoint_id"
+          ],
+          "columnsTo": [
+            "company_id",
+            "id"
+          ],
+          "onDelete": "cascade",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "policies": {},
+      "checkConstraints": {
+        "chat_github_registration_status_check": {
+          "name": "chat_github_registration_status_check",
+          "value": "\"chat_github_registrations\".\"status\" in ('pending', 'exchanging', 'completed', 'failed')"
+        }
+      },
+      "isRLSEnabled": false
+    },
+    "public.chat_github_reviews": {
+      "name": "chat_github_reviews",
+      "schema": "",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "uuid",
+          "primaryKey": true,
+          "notNull": true,
+          "default": "gen_random_uuid()"
+        },
+        "company_id": {
+          "name": "company_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "endpoint_id": {
+          "name": "endpoint_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "issue_id": {
+          "name": "issue_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "run_id": {
+          "name": "run_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "repository_id": {
+          "name": "repository_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "repository": {
+          "name": "repository",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "pull_number": {
+          "name": "pull_number",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "head_sha": {
+          "name": "head_sha",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "delivery_id": {
+          "name": "delivery_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "configuration_revision": {
+          "name": "configuration_revision",
+          "type": "integer",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "policy_snapshot": {
+          "name": "policy_snapshot",
+          "type": "jsonb",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "event": {
+          "name": "event",
+          "type": "jsonb",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "state": {
+          "name": "state",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "'queued'"
+        },
+        "assessment": {
+          "name": "assessment",
+          "type": "jsonb",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "conclusion": {
+          "name": "conclusion",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "check_id": {
+          "name": "check_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "check_url": {
+          "name": "check_url",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "summary_id": {
+          "name": "summary_id",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "summary_url": {
+          "name": "summary_url",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": false
+        },
+        "publication_receipts": {
+          "name": "publication_receipts",
+          "type": "jsonb",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "'{}'::jsonb"
+        },
+        "created_at": {
+          "name": "created_at",
+          "type": "timestamp with time zone",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        },
+        "updated_at": {
+          "name": "updated_at",
+          "type": "timestamp with time zone",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        }
+      },
+      "indexes": {
+        "chat_github_reviews_delivery_uq": {
+          "name": "chat_github_reviews_delivery_uq",
+          "columns": [
+            {
+              "expression": "endpoint_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            },
+            {
+              "expression": "delivery_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            }
+          ],
+          "isUnique": true,
+          "concurrently": false,
+          "method": "btree",
+          "with": {}
+        },
+        "chat_github_reviews_pull_idx": {
+          "name": "chat_github_reviews_pull_idx",
+          "columns": [
+            {
+              "expression": "endpoint_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            },
+            {
+              "expression": "repository_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            },
+            {
+              "expression": "pull_number",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            },
+            {
+              "expression": "created_at",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            }
+          ],
+          "isUnique": false,
+          "concurrently": false,
+          "method": "btree",
+          "with": {}
+        },
+        "chat_github_reviews_task_idx": {
+          "name": "chat_github_reviews_task_idx",
+          "columns": [
+            {
+              "expression": "company_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            },
+            {
+              "expression": "issue_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            },
+            {
+              "expression": "run_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            }
+          ],
+          "isUnique": false,
+          "concurrently": false,
+          "method": "btree",
+          "with": {}
+        }
+      },
+      "foreignKeys": {
+        "chat_github_reviews_run_id_heartbeat_runs_id_fk": {
+          "name": "chat_github_reviews_run_id_heartbeat_runs_id_fk",
+          "tableFrom": "chat_github_reviews",
+          "tableTo": "heartbeat_runs",
+          "columnsFrom": [
+            "run_id"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "set null",
+          "onUpdate": "no action"
+        },
+        "chat_github_reviews_company_id_endpoint_id_chat_endpoints_company_id_id_fk": {
+          "name": "chat_github_reviews_company_id_endpoint_id_chat_endpoints_company_id_id_fk",
+          "tableFrom": "chat_github_reviews",
+          "tableTo": "chat_endpoints",
+          "columnsFrom": [
+            "company_id",
+            "endpoint_id"
+          ],
+          "columnsTo": [
+            "company_id",
+            "id"
+          ],
+          "onDelete": "cascade",
+          "onUpdate": "no action"
+        },
+        "chat_github_reviews_company_id_issue_id_issues_company_id_id_fk": {
+          "name": "chat_github_reviews_company_id_issue_id_issues_company_id_id_fk",
+          "tableFrom": "chat_github_reviews",
+          "tableTo": "issues",
+          "columnsFrom": [
+            "company_id",
+            "issue_id"
+          ],
+          "columnsTo": [
+            "company_id",
+            "id"
+          ],
+          "onDelete": "restrict",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {
+        "chat_github_reviews_company_id_uq": {
+          "name": "chat_github_reviews_company_id_uq",
+          "nullsNotDistinct": false,
+          "columns": [
+            "company_id",
+            "id"
+          ]
+        }
+      },
+      "policies": {},
+      "checkConstraints": {
+        "chat_github_review_pull_number_check": {
+          "name": "chat_github_review_pull_number_check",
+          "value": "\"chat_github_reviews\".\"pull_number\" > 0"
+        },
+        "chat_github_review_state_check": {
+          "name": "chat_github_review_state_check",
+          "value": "\"chat_github_reviews\".\"state\" in ('queued', 'running', 'completed', 'incomplete', 'error', 'superseded', 'manual_required')"
+        }
+      },
+      "isRLSEnabled": false
+    },
     "public.chat_teams_file_transfers": {
       "name": "chat_teams_file_transfers",
       "schema": "",
@@ -37416,6 +38201,26 @@
           "notNull": true,
           "default": true
         },
+        "setup_pending": {
+          "name": "setup_pending",
+          "type": "boolean",
+          "primaryKey": false,
+          "notNull": true,
+          "default": false
+        },
+        "archived": {
+          "name": "archived",
+          "type": "boolean",
+          "primaryKey": false,
+          "notNull": true,
+          "default": false
+        },
+        "last_webhook_delivery": {
+          "name": "last_webhook_delivery",
+          "type": "jsonb",
+          "primaryKey": false,
+          "notNull": false
+        },
         "cron_expression": {
           "name": "cron_expression",
           "type": "text",
@@ -37677,6 +38482,100 @@
       "checkConstraints": {},
       "isRLSEnabled": false
     },
+    "public.routine_webhook_test_receipts": {
+      "name": "routine_webhook_test_receipts",
+      "schema": "",
+      "columns": {
+        "id": {
+          "name": "id",
+          "type": "uuid",
+          "primaryKey": true,
+          "notNull": true,
+          "default": "gen_random_uuid()"
+        },
+        "company_id": {
+          "name": "company_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "trigger_id": {
+          "name": "trigger_id",
+          "type": "uuid",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "delivery_key_hash": {
+          "name": "delivery_key_hash",
+          "type": "text",
+          "primaryKey": false,
+          "notNull": true
+        },
+        "received_at": {
+          "name": "received_at",
+          "type": "timestamp with time zone",
+          "primaryKey": false,
+          "notNull": true,
+          "default": "now()"
+        }
+      },
+      "indexes": {
+        "routine_webhook_test_receipts_delivery_uq": {
+          "name": "routine_webhook_test_receipts_delivery_uq",
+          "columns": [
+            {
+              "expression": "trigger_id",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            },
+            {
+              "expression": "delivery_key_hash",
+              "isExpression": false,
+              "asc": true,
+              "nulls": "last"
+            }
+          ],
+          "isUnique": true,
+          "concurrently": false,
+          "method": "btree",
+          "with": {}
+        }
+      },
+      "foreignKeys": {
+        "routine_webhook_test_receipts_company_id_companies_id_fk": {
+          "name": "routine_webhook_test_receipts_company_id_companies_id_fk",
+          "tableFrom": "routine_webhook_test_receipts",
+          "tableTo": "companies",
+          "columnsFrom": [
+            "company_id"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "cascade",
+          "onUpdate": "no action"
+        },
+        "routine_webhook_test_receipts_trigger_id_routine_triggers_id_fk": {
+          "name": "routine_webhook_test_receipts_trigger_id_routine_triggers_id_fk",
+          "tableFrom": "routine_webhook_test_receipts",
+          "tableTo": "routine_triggers",
+          "columnsFrom": [
+            "trigger_id"
+          ],
+          "columnsTo": [
+            "id"
+          ],
+          "onDelete": "cascade",
+          "onUpdate": "no action"
+        }
+      },
+      "compositePrimaryKeys": {},
+      "uniqueConstraints": {},
+      "policies": {},
+      "checkConstraints": {},
+      "isRLSEnabled": false
+    },
     "public.routines": {
       "name": "routines",
       "schema": "",
diff --git a/packages/db/src/migrations/meta/_journal.json b/packages/db/src/migrations/meta/_journal.json
index a46ca4cfb44..b5de2bf5add 100644
--- a/packages/db/src/migrations/meta/_journal.json
+++ b/packages/db/src/migrations/meta/_journal.json
@@ -1982,6 +1982,13 @@
       "when": 1790439010225,
       "tag": "0284_petite_genesis",
       "breakpoints": true
+    },
+    {
+      "idx": 285,
+      "version": "7",
+      "when": 1790474441205,
+      "tag": "0285_legal_thunderbolts",
+      "breakpoints": true
     }
   ]
 }
\ No newline at end of file
diff --git a/packages/db/src/schema/agent_instruction_revisions.ts b/packages/db/src/schema/agent_instruction_revisions.ts
new file mode 100644
index 00000000000..f550c74c4db
--- /dev/null
+++ b/packages/db/src/schema/agent_instruction_revisions.ts
@@ -0,0 +1,84 @@
+import {
+  pgTable,
+  uuid,
+  text,
+  integer,
+  timestamp,
+  index,
+  unique,
+  foreignKey,
+} from "drizzle-orm/pg-core";
+import { agents } from "./agents.js";
+
+/** Append-only content. Base64 preserves every UTF-8 byte, including NUL and BOM. */
+export const agentInstructionRevisions = pgTable(
+  "agent_instruction_revisions",
+  {
+    id: uuid("id").primaryKey().defaultRandom(),
+    companyId: uuid("company_id").notNull(),
+    agentId: uuid("agent_id").notNull(),
+    entryFile: text("entry_file").notNull(),
+    contentBase64: text("content_base64").notNull(),
+    contentHash: text("content_hash").notNull(),
+    byteLength: integer("byte_length").notNull(),
+    parentRevisionId: uuid("parent_revision_id"),
+    baseRevisionId: uuid("base_revision_id"),
+    restoredFromRevisionId: uuid("restored_from_revision_id"),
+    actorAgentId: uuid("actor_agent_id"),
+    actorUserId: text("actor_user_id"),
+    responsibleUserId: text("responsible_user_id"),
+    sourceRunId: uuid("source_run_id"),
+    source: text("source").notNull(),
+    createdAt: timestamp("created_at", { withTimezone: true })
+      .notNull()
+      .defaultNow(),
+  },
+  (t) => ({
+    owner: foreignKey({
+      columns: [t.companyId, t.agentId],
+      foreignColumns: [agents.companyId, agents.id],
+    }).onDelete("cascade"),
+    identity: unique("agent_instruction_revisions_identity_uq").on(
+      t.companyId,
+      t.agentId,
+      t.entryFile,
+      t.id,
+    ),
+    history: index("agent_instruction_revisions_history_idx").on(
+      t.companyId,
+      t.agentId,
+      t.entryFile,
+      t.createdAt,
+      t.id,
+    ),
+  }),
+);
+
+export const agentInstructionHeads = pgTable(
+  "agent_instruction_heads",
+  {
+    companyId: uuid("company_id").notNull(),
+    agentId: uuid("agent_id").notNull(),
+    entryFile: text("entry_file").notNull(),
+    revisionId: uuid("revision_id").notNull(),
+    updatedAt: timestamp("updated_at", { withTimezone: true })
+      .notNull()
+      .defaultNow(),
+  },
+  (t) => ({
+    identity: unique("agent_instruction_heads_identity_uq").on(
+      t.companyId,
+      t.agentId,
+      t.entryFile,
+    ),
+    revision: foreignKey({
+      columns: [t.companyId, t.agentId, t.entryFile, t.revisionId],
+      foreignColumns: [
+        agentInstructionRevisions.companyId,
+        agentInstructionRevisions.agentId,
+        agentInstructionRevisions.entryFile,
+        agentInstructionRevisions.id,
+      ],
+    }).onDelete("cascade"),
+  }),
+);
diff --git a/packages/db/src/schema/index.ts b/packages/db/src/schema/index.ts
index 81ea3bc33bb..305033b6366 100644
--- a/packages/db/src/schema/index.ts
+++ b/packages/db/src/schema/index.ts
@@ -210,3 +210,5 @@ export { aiConnectionDefaults } from "./ai_connection_defaults.js";
 export { aiProviderDefaults } from "./ai_provider_defaults.js";
 export * from "./email.js";
 export { announcementDismissals, announcementPublications } from "./announcement_dismissals.js";
+
+export { agentInstructionRevisions, agentInstructionHeads } from "./agent_instruction_revisions.js";
diff --git a/packages/shared/src/index.ts b/packages/shared/src/index.ts
index 9ae73b45045..15f458a5e4c 100644
--- a/packages/shared/src/index.ts
+++ b/packages/shared/src/index.ts
@@ -2788,3 +2788,6 @@ export { MEMORY_CONNECTOR_IDS, isMemoryConnectorId, type MemoryConnectorId } fro
 export * from "./connection-routing.js";
 
 export { WORKSPACE_RESTORE_FAILURE_CODES, hasWorkspaceRestoreFailure, safeWorkspaceRestorePath } from "./workspace-restore.js";
+
+export type { AgentInstructionErrorCode, AgentInstructionErrorDetails, AgentInstructionSource, AgentInstructionRevision, AgentInstructionSnapshot, AgentInstructionCommitReceipt, AgentInstructionHistory, AgentInstructionDiff } from "./types/agent.js";
+export { restoreAgentInstructionSchema } from "./validators/agent.js";
diff --git a/packages/shared/src/types/agent.ts b/packages/shared/src/types/agent.ts
index e775c5b9941..cda07d1c7b2 100644
--- a/packages/shared/src/types/agent.ts
+++ b/packages/shared/src/types/agent.ts
@@ -43,6 +43,8 @@ export interface AgentInstructionsFileSummary {
 
 export interface AgentInstructionsFileDetail extends AgentInstructionsFileSummary {
   content: string;
+  revision?: AgentInstructionRevision;
+  receipt?: AgentInstructionCommitReceipt;
 }
 
 export interface AgentInstructionsBundle {
@@ -336,3 +338,61 @@ export type AdapterAuthSignal = "present" | "absent" | "unknown";
 export interface AdapterAuthSignalResponse {
   status: AdapterAuthSignal;
 }
+
+export type AgentInstructionSource = "seed" | "board" | "api" | "tool" | "cleanup" | "restore";
+export interface AgentInstructionRevision {
+  id: string;
+  companyId: string;
+  agentId: string;
+  entryFile: string;
+  contentHash: string;
+  byteLength: number;
+  parentRevisionId: string | null;
+  baseRevisionId: string | null;
+  restoredFromRevisionId: string | null;
+  actorAgentId: string | null;
+  actorUserId: string | null;
+  responsibleUserId: string | null;
+  sourceRunId: string | null;
+  source: AgentInstructionSource;
+  createdAt: string;
+}
+export interface AgentInstructionSnapshot {
+  revision: AgentInstructionRevision;
+  content: string;
+}
+export interface AgentInstructionCommitReceipt extends AgentInstructionSnapshot {
+  changed: boolean;
+  materialization: "current" | "pending";
+}
+export interface AgentInstructionHistory {
+  revisions: AgentInstructionRevision[];
+  nextCursor: string | null;
+}
+export interface AgentInstructionDiff {
+  from: AgentInstructionSnapshot;
+  to: AgentInstructionSnapshot;
+  prefix: string;
+  removed: string;
+  added: string;
+  suffix: string;
+}
+
+export type AgentInstructionErrorCode =
+  | "INSTRUCTION_BASE_REQUIRED"
+  | "INSTRUCTION_REVISION_REQUIRED"
+  | "INSTRUCTION_REVISION_CONFLICT"
+  | "INSTRUCTION_ENTRY_CHANGED"
+  | "INSTRUCTION_MANAGED_BUNDLE_REQUIRED"
+  | "INSTRUCTION_IDENTITY_INVALID"
+  | "INSTRUCTION_CONTENT_INVALID"
+  | "INSTRUCTION_PATH_INVALID"
+  | "RESPONSIBLE_USER_UNAVAILABLE"
+  | "RESPONSIBLE_USER_UNAUTHORIZED";
+export interface AgentInstructionErrorDetails {
+  code: AgentInstructionErrorCode;
+  baseRevisionId?: string | null;
+  currentRevisionId?: string | null;
+  entryFile?: string;
+  reason?: string;
+}
diff --git a/packages/shared/src/types/index.ts b/packages/shared/src/types/index.ts
index 179832a3de4..b9dd9c280c0 100644
--- a/packages/shared/src/types/index.ts
+++ b/packages/shared/src/types/index.ts
@@ -1069,3 +1069,5 @@ export * from "./chat-channels.js";
 export * from "./chat-github.js";
 
 export * from "./email.js";
+
+export type { AgentInstructionErrorCode, AgentInstructionErrorDetails, AgentInstructionSource, AgentInstructionRevision, AgentInstructionSnapshot, AgentInstructionCommitReceipt, AgentInstructionHistory, AgentInstructionDiff } from "./agent.js";
diff --git a/packages/shared/src/validators/agent.ts b/packages/shared/src/validators/agent.ts
index e40a7cf6ce7..3086c4f30ae 100644
--- a/packages/shared/src/validators/agent.ts
+++ b/packages/shared/src/validators/agent.ts
@@ -34,10 +34,17 @@ export const updateAgentInstructionsBundleSchema = z.object({
 export type UpdateAgentInstructionsBundle = z.infer<typeof updateAgentInstructionsBundleSchema>;
 
 export const upsertAgentInstructionsFileSchema = z.object({
-  path: z.string().trim().min(1),
-  content: z.string(),
+  path: z.string().min(1).max(512),
+  content: z.string().max(1024 * 1024),
+  baseRevisionId: z.string().uuid().nullable().optional(),
   clearLegacyPromptTemplate: z.boolean().optional().default(false),
-});
+}).strict();
+
+export const restoreAgentInstructionSchema = z.object({
+  path: z.string().min(1).max(512),
+  revisionId: z.string().uuid(),
+  baseRevisionId: z.string().uuid(),
+}).strict();
 
 export type UpsertAgentInstructionsFile = z.infer<typeof upsertAgentInstructionsFileSchema>;
 
diff --git a/packages/shared/src/validators/index.ts b/packages/shared/src/validators/index.ts
index 09c4fef7c4c..2b00f4cab09 100644
--- a/packages/shared/src/validators/index.ts
+++ b/packages/shared/src/validators/index.ts
@@ -984,3 +984,5 @@ export * from "./chat-channels.js";
 export * from "./chat-github.js";
 
 export * from "./email.js";
+
+export { restoreAgentInstructionSchema } from "./agent.js";
diff --git a/server/src/__tests__/agent-instruction-revisions.test.ts b/server/src/__tests__/agent-instruction-revisions.test.ts
new file mode 100644
index 00000000000..1af2f642e4e
--- /dev/null
+++ b/server/src/__tests__/agent-instruction-revisions.test.ts
@@ -0,0 +1,240 @@
+import fs from "node:fs/promises";
+import os from "node:os";
+import path from "node:path";
+import { randomUUID } from "node:crypto";
+import { beforeAll, afterAll, beforeEach, describe, expect, it, vi } from "vitest";
+import { and, eq, sql } from "drizzle-orm";
+import { agents, agentApiKeys, companies, authUsers, companyMemberships, principalPermissionGrants, heartbeatRuns,
+  agentInstructionRevisions, agentInstructionHeads, issueThreadInteractions, issues, createDb } from "@paperclipai/db";
+import { startEmbeddedPostgresTestDatabase } from "./helpers/embedded-postgres.js";
+import { agentInstructionRevisionService } from "../services/agent-instruction-revisions.js";
+import { instructionBytes, instructionPath, readInstructionBytes } from "../services/agent-instruction-files.js";
+import { agentInstructionsService, resolveManagedInstructionsRoot } from "../services/agent-instructions.js";
+import type { AuthorizationActor } from "../services/authorization.js";
+import { upsertAgentInstructionsFileSchema } from "@paperclipai/shared";
+
+describe("canonical instruction revisions", () => {
+  let database: Awaited<ReturnType<typeof startEmbeddedPostgresTestDatabase>>;
+  let db: ReturnType<typeof createDb>;
+  let service: ReturnType<typeof agentInstructionRevisionService>;
+  const previousHome = process.env.PAPERCLIP_HOME;
+  let home: string;
+  let companyId: string, agentId: string, userId: string, actorId: string, runId: string, root: string;
+  let actor: AuthorizationActor;
+  const entryFile = "policy/INSTRUCTIONS.txt";
+  const initial = "\uFEFF# Original\r\n☃\0\n";
+  beforeAll(async () => {
+    home = await fs.mkdtemp(path.join(os.tmpdir(), "instruction-revisions-"));
+    process.env.PAPERCLIP_HOME = home;
+    database = await startEmbeddedPostgresTestDatabase("instruction-revisions-db-");
+    db = createDb(database.connectionString);
+    service = agentInstructionRevisionService(db);
+  }, 90_000);
+  afterAll(async () => {
+    vi.restoreAllMocks();
+    if (previousHome === undefined) delete process.env.PAPERCLIP_HOME; else process.env.PAPERCLIP_HOME = previousHome;
+    await database?.cleanup();
+    if (home) await fs.rm(home, { recursive: true, force: true });
+  });
+  beforeEach(async () => {
+    companyId = randomUUID(); agentId = randomUUID(); actorId = randomUUID(); userId = randomUUID(); runId = randomUUID();
+    await db.insert(companies).values({ id: companyId, name: "Instruction tests", issuePrefix: randomUUID().slice(0, 8) });
+    await db.insert(authUsers).values({ id: userId, name: "Editor", email: `${userId}@example.test`, createdAt: new Date(), updatedAt: new Date() });
+    root = resolveManagedInstructionsRoot({ id: agentId, companyId, name: "Target", adapterConfig: {} });
+    await db.insert(agents).values([
+      { id: agentId, companyId, name: "Target", adapterConfig: { instructionsBundleMode: "managed", instructionsRootPath: root, instructionsEntryFile: entryFile } },
+      { id: actorId, companyId, name: "Writer" },
+    ]);
+    await db.insert(companyMemberships).values([
+      { companyId, principalType: "user", principalId: userId, membershipRole: "operator" },
+      { companyId, principalType: "agent", principalId: actorId, membershipRole: "member" },
+    ]);
+    await db.insert(principalPermissionGrants).values({ companyId, principalType: "user", principalId: userId, permissionKey: "agents:configure", scope: { agentIds: [agentId] } });
+    await db.insert(heartbeatRuns).values({ id: runId, companyId, agentId: actorId, invocationSource: "on_demand", responsibleUserId: userId });
+    actor = { type: "agent", companyId, agentId: actorId, runId, source: "agent_jwt" };
+    await fs.mkdir(path.dirname(path.join(root, entryFile)), { recursive: true });
+    await fs.writeFile(path.join(root, entryFile), initial);
+  });
+  const target = () => ({ companyId, agentId });
+  async function base() { return (await service.readCurrent(target(), actor))!; }
+  async function save(content: string, baseRevisionId: string | null) {
+    return service.commit({ ...target(), entryFile, content, baseRevisionId, source: "cleanup" }, actor);
+  }
+  it("seeds configured bytes, preserves immutable history, deduplicates, diffs and restores as a new revision", async () => {
+    const first = await base();
+    expect(first.content).toBe(initial);
+    expect(first.revision).toMatchObject({ entryFile, source: "seed", responsibleUserId: userId, actorAgentId: actorId, sourceRunId: runId });
+    const saved = await save("# Changed\r\n", first.revision.id);
+    expect(saved).toMatchObject({ changed: true, materialization: "current", revision: { parentRevisionId: first.revision.id, baseRevisionId: first.revision.id } });
+    expect(await fs.readFile(path.join(root, entryFile), "utf8")).toBe(saved.content);
+    expect((await save(saved.content, first.revision.id)).revision.id).toBe(saved.revision.id);
+    const diff = await service.diff({ ...target(), entryFile, fromRevisionId: first.revision.id, toRevisionId: saved.revision.id }, actor);
+    expect(diff.prefix + diff.removed + diff.suffix).toBe(initial);
+    expect(diff.prefix + diff.added + diff.suffix).toBe(saved.content);
+    const restored = await service.restore({ ...target(), entryFile, revisionId: first.revision.id, baseRevisionId: saved.revision.id }, actor);
+    expect(restored.content).toBe(initial);
+    expect(restored.revision).toMatchObject({ source: "restore", parentRevisionId: saved.revision.id, restoredFromRevisionId: first.revision.id });
+    expect(restored.revision.id).not.toBe(first.revision.id);
+    expect((await service.history({ ...target(), entryFile }, actor)).revisions).toHaveLength(3);
+    const page = await service.history({ ...target(), entryFile, limit: 1 }, actor);
+    expect((await service.history({ ...target(), entryFile, cursor: page.nextCursor!, limit: 1 }, actor)).revisions[0].id).toBe(saved.revision.id);
+  });
+  it("does not expose a rolled-back seed revision when a writer omitted the initial read", async () => {
+    await expect(save("overwrite without reading", null)).rejects.toMatchObject({ status: 409, details: { currentRevisionId: null } });
+    expect(await db.select().from(agentInstructionRevisions).where(eq(agentInstructionRevisions.agentId, agentId))).toHaveLength(0);
+    expect((await base()).content).toBe(initial);
+  });
+  it("paginates without dropping revisions within one fractional millisecond", async () => {
+    const first = await base();
+    const second = await save("second", first.revision.id);
+    const third = await save("third", second.revision.id);
+    // Give this fixture timestamps that JS Date cannot represent exactly.
+    for (const [id, time] of [[first.revision.id, "2026-01-01 00:00:00.123100+00"], [second.revision.id, "2026-01-01 00:00:00.123200+00"], [third.revision.id, "2026-01-01 00:00:00.123300+00"]]) {
+      await db.execute(sql`update agent_instruction_revisions set created_at = ${time}::timestamptz where id = ${id}`);
+    }
+    const a = await service.history({ ...target(), entryFile, limit: 1 }, actor);
+    const b = await service.history({ ...target(), entryFile, limit: 1, cursor: a.nextCursor! }, actor);
+    const c = await service.history({ ...target(), entryFile, limit: 1, cursor: b.nextCursor! }, actor);
+    expect([a, b, c].map((page) => page.revisions[0].id)).toEqual([third.revision.id, second.revision.id, first.revision.id]);
+    expect(c.nextCursor).toBeNull();
+  });
+  it("serializes competing saves and refuses stale cleanup after a restore or board edit", async () => {
+    const first = await base();
+    const results = await Promise.allSettled([save("one", first.revision.id), save("two", first.revision.id)]);
+    expect(results.filter((r) => r.status === "fulfilled")).toHaveLength(1);
+    expect(results.find((r) => r.status === "rejected")).toMatchObject({ reason: { status: 409, details: { code: "INSTRUCTION_REVISION_CONFLICT" } } });
+    expect((await service.history({ ...target(), entryFile }, actor)).revisions).toHaveLength(2);
+    const current = await base();
+    await service.restore({ ...target(), entryFile, baseRevisionId: current.revision.id, revisionId: first.revision.id }, actor);
+    await expect(save("stale cleanup", current.revision.id)).rejects.toMatchObject({ status: 409 });
+  });
+  it("commits before materializing and recovers the committed head after a new service instance", async () => {
+    const first = await base();
+    const rename = vi.spyOn(fs, "rename").mockRejectedValueOnce(new Error("simulated interrupted materialization"));
+    const saved = await save("durable", first.revision.id);
+    rename.mockRestore();
+    expect(saved.materialization).toBe("pending");
+    expect(await fs.readFile(path.join(root, entryFile), "utf8")).toBe(initial);
+    service = agentInstructionRevisionService(db);
+    expect((await base()).content).toBe("durable");
+    await service.materializeCurrent(target());
+    expect(await fs.readFile(path.join(root, entryFile), "utf8")).toBe("durable");
+    await fs.unlink(path.join(root, entryFile));
+    await service.materializeCurrent(target());
+    expect(await fs.readFile(path.join(root, entryFile), "utf8")).toBe("durable");
+  });
+  it("rolls back revision and head together when the database rejects head movement", async () => {
+    const first = await base();
+    await db.execute(sql`CREATE FUNCTION reject_instruction_head_test() RETURNS trigger LANGUAGE plpgsql AS $$ BEGIN RAISE EXCEPTION 'injected head failure'; END $$`);
+    await db.execute(sql`CREATE TRIGGER reject_instruction_head_test BEFORE UPDATE ON agent_instruction_heads FOR EACH ROW EXECUTE FUNCTION reject_instruction_head_test()`);
+    try { await expect(save("lost", first.revision.id)).rejects.toThrow(); }
+    finally { await db.execute(sql`DROP TRIGGER reject_instruction_head_test ON agent_instruction_heads`); await db.execute(sql`DROP FUNCTION reject_instruction_head_test()`); }
+    expect((await base()).revision.id).toBe(first.revision.id);
+    expect((await service.history({ ...target(), entryFile }, actor)).revisions).toHaveLength(1);
+  });
+  it("allows ordinary peer edits without agent-admin but rejects missing, forged and revoked responsible identity", async () => {
+    const first = await base();
+    await save("peer save", first.revision.id);
+    await expect(service.commit({ ...target(), entryFile, content: "forged", baseRevisionId: first.revision.id, source: "tool" }, { ...actor, onBehalfOfUserId: "forged" })).rejects.toMatchObject({ status: 403 });
+    await db.update(heartbeatRuns).set({ responsibleUserId: null }).where(eq(heartbeatRuns.id, runId));
+    await expect(save("missing", first.revision.id)).rejects.toMatchObject({ status: 403 });
+    await db.update(heartbeatRuns).set({ responsibleUserId: userId }).where(eq(heartbeatRuns.id, runId));
+    await db.update(companyMemberships).set({ status: "suspended" }).where(and(eq(companyMemberships.principalId, userId), eq(companyMemberships.companyId, companyId)));
+    await expect(save("revoked", first.revision.id)).rejects.toMatchObject({ status: 403 });
+  });
+  it("rechecks user target scope and agent containment, even with shadow authorization enabled", async () => {
+    const first = await base();
+    const previousShadow = process.env.PAPERCLIP_RESPONSIBLE_USER_AUTHZ_SHADOW;
+    process.env.PAPERCLIP_RESPONSIBLE_USER_AUTHZ_SHADOW = "true";
+    await db.update(principalPermissionGrants).set({ scope: { agentIds: [actorId] } }).where(eq(principalPermissionGrants.principalId, userId));
+    await expect(save("denied", first.revision.id)).rejects.toMatchObject({ status: 403 });
+    await db.update(principalPermissionGrants).set({ scope: null }).where(eq(principalPermissionGrants.principalId, userId));
+    await db.update(agents).set({ permissions: { trustPreset: "low_trust_review" } }).where(eq(agents.id, actorId));
+    await expect(save("restricted", first.revision.id)).rejects.toMatchObject({ status: 403 });
+    if (previousShadow === undefined) delete process.env.PAPERCLIP_RESPONSIBLE_USER_AUTHZ_SHADOW; else process.env.PAPERCLIP_RESPONSIBLE_USER_AUTHZ_SHADOW = previousShadow;
+  });
+  it("keeps suggest-only protected-change consent and explicit configure scope restrictions", async () => {
+    const first = await base();
+    await db.insert(principalPermissionGrants).values({ companyId, principalType: "agent", principalId: actorId, permissionKey: "agents:suggest-changes" });
+    await expect(save("needs approval", first.revision.id)).rejects.toMatchObject({ status: 403 });
+    await db.delete(principalPermissionGrants).where(eq(principalPermissionGrants.principalId, actorId));
+    await db.insert(principalPermissionGrants).values({ companyId, principalType: "agent", principalId: actorId, permissionKey: "agents:configure", scope: { agentIds: [actorId] } });
+    await expect(save("out of scope", first.revision.id)).rejects.toMatchObject({ status: 403 });
+  });
+  it("consumes accepted protected-change approval only with a successful CAS commit", async () => {
+    const first = await base();
+    const sourceRunId = randomUUID(), issueId = randomUUID(), interactionId = randomUUID();
+    await db.insert(heartbeatRuns).values({ id: sourceRunId, companyId, agentId: actorId, status: "succeeded" });
+    await db.insert(issues).values({ id: issueId, companyId, title: "Review instructions" });
+    await db.insert(principalPermissionGrants).values({ companyId, principalType: "agent", principalId: actorId, permissionKey: "agents:suggest-changes" });
+    await db.insert(issueThreadInteractions).values({ id: interactionId, companyId, issueId, kind: "request_confirmation", status: "accepted", sourceRunId, createdByAgentId: actorId,
+      payload: { version: 1, prompt: "Apply the instruction change?", detailsMarkdown: "```diff\n+approved\n```", target: { type: "custom", key: `agent:${agentId}:instructions`, revisionId: "proposal" } },
+      result: { version: 1, outcome: "accepted" }, resolvedByUserId: userId, resolvedAt: new Date(),
+    });
+    await expect(save("approved", randomUUID())).rejects.toMatchObject({ status: 409 });
+    expect((await db.select().from(issueThreadInteractions).where(eq(issueThreadInteractions.id, interactionId)))[0].result).not.toHaveProperty("consumedAt");
+    const receipt = await save("approved", first.revision.id);
+    expect(receipt.changed).toBe(true);
+    expect((await db.select().from(issueThreadInteractions).where(eq(issueThreadInteractions.id, interactionId)))[0].result).toMatchObject({ consumedByRunId: runId });
+    await expect(save("another unapproved change", receipt.revision.id)).rejects.toMatchObject({ status: 403 });
+  });
+  it("shares head/CAS and attribution between board and agent writers", async () => {
+    const first = await base();
+    const board = { type: "board", userId, source: "session" } as const;
+    const saved = await service.commit({ ...target(), entryFile, content: "board edit", baseRevisionId: first.revision.id, source: "board" }, board);
+    expect(saved.revision).toMatchObject({ actorUserId: userId, responsibleUserId: userId, actorAgentId: null, sourceRunId: null, source: "board" });
+    await expect(save("stale agent edit", first.revision.id)).rejects.toMatchObject({ status: 409 });
+  });
+  it("seeds a nested legacy managed entry and never imports a different AGENTS.md", async () => {
+    await fs.writeFile(path.join(root, "AGENTS.md"), "unrelated");
+    await db.update(agents).set({ adapterConfig: { instructionsFilePath: path.join(root, entryFile) } }).where(eq(agents.id, agentId));
+    const first = await base();
+    expect(first.content).toBe(initial);
+    expect(first.revision.entryFile).toBe(entryFile);
+    await db.update(agents).set({ adapterConfig: { instructionsBundleMode: "managed", instructionsRootPath: root, instructionsEntryFile: "missing.md" } }).where(eq(agents.id, agentId));
+    expect(await service.readCurrent(target(), actor)).toBeNull();
+    await expect(save("wrong entry", first.revision.id)).rejects.toMatchObject({ status: 409, details: { code: "INSTRUCTION_ENTRY_CHANGED" } });
+  });
+  it("rejects cross-company targets, foreign revisions, and revoked API keys", async () => {
+    const first = await base();
+    await expect(service.readRevision({ ...target(), entryFile, revisionId: randomUUID() }, actor)).rejects.toMatchObject({ status: 404 });
+    await expect(service.readCurrent({ companyId: randomUUID(), agentId }, actor)).rejects.toMatchObject({ status: 404 });
+    const keyId = randomUUID();
+    await db.insert(agentApiKeys).values({ id: keyId, companyId, agentId: actorId, name: "test", keyHash: randomUUID(), responsibleUserId: userId, revokedAt: new Date() });
+    await expect(service.commit({ ...target(), entryFile, content: "key", baseRevisionId: first.revision.id, source: "api" }, { ...actor, keyId })).rejects.toMatchObject({ status: 403 });
+    await expect(db.insert(agentInstructionHeads).values({ companyId: randomUUID(), agentId, entryFile, revisionId: first.revision.id })).rejects.toThrow();
+  });
+  it("rejects invalid content, symlinks, traversal and external bundles without changing canonical bytes", async () => {
+    const first = await base();
+    expect(() => instructionBytes("\ud800")).toThrow("UTF-8");
+    expect(() => instructionBytes(new Uint8Array([0xff]))).toThrow("UTF-8");
+    expect(() => instructionBytes("a".repeat(1024 * 1024 + 1))).toThrow("1 MiB");
+    for (const value of ["../AGENTS.md", "/etc/passwd", "a/../AGENTS.md", "a\\b", "a//b"]) expect(() => instructionPath(value)).toThrow();
+    await fs.unlink(path.join(root, entryFile));
+    await fs.symlink(path.join(home, "outside"), path.join(root, entryFile));
+    await expect(save("symlink", first.revision.id)).rejects.toMatchObject({ status: 422 });
+    await fs.unlink(path.join(root, entryFile));
+    await fs.rm(path.dirname(path.join(root, entryFile)), { recursive: true });
+    await fs.symlink(home, path.dirname(path.join(root, entryFile)));
+    await expect(readInstructionBytes(root, entryFile)).rejects.toMatchObject({ status: 422 });
+    await db.update(agents).set({ adapterConfig: { instructionsBundleMode: "external", instructionsRootPath: home } }).where(eq(agents.id, agentId));
+    await expect(save("external", first.revision.id)).rejects.toMatchObject({ details: { code: "INSTRUCTION_MANAGED_BUNDLE_REQUIRED" } });
+    expect((await db.select().from(agentInstructionRevisions).where(eq(agentInstructionRevisions.agentId, agentId)))).toHaveLength(1);
+  });
+  it("does not overwrite history through bundle replacement or unversioned entry writers", async () => {
+    await base();
+    const [agent] = await db.select().from(agents).where(eq(agents.id, agentId));
+    await expect(agentInstructionsService(db).writeFile(agent, entryFile, "bypass")).rejects.toMatchObject({ details: { code: "INSTRUCTION_REVISION_REQUIRED" } });
+    await expect(agentInstructionsService(db).materializeManagedBundle(agent, { [entryFile]: "bypass" }, { entryFile, replaceExisting: true })).rejects.toMatchObject({ details: { code: "INSTRUCTION_REVISION_REQUIRED" } });
+    const files = agentInstructionsService(db);
+    await db.update(agents).set({ adapterConfig: { ...agent.adapterConfig, instructionsEntryFile: "NEXT.md", instructionsFilePath: path.join(root, "NEXT.md") } }).where(eq(agents.id, agentId));
+    await fs.writeFile(path.join(root, "NEXT.md"), "new configured entry");
+    // A route's stale agent snapshot must not classify the new entry as supporting content.
+    await expect(files.writeFile(agent, "NEXT.md", "bypass")).rejects.toMatchObject({ details: { code: "INSTRUCTION_REVISION_REQUIRED" } });
+    await expect(files.deleteFile(agent, "NEXT.md")).rejects.toMatchObject({ status: 422 });
+    await expect(files.writeFile(agent, entryFile, "historical bypass")).rejects.toMatchObject({ details: { code: "INSTRUCTION_REVISION_REQUIRED" } });
+    await expect(files.materializeManagedBundle(agent, { "NEXT.md": "new configured entry" }, { entryFile: "NEXT.md", replaceExisting: true })).rejects.toMatchObject({ details: { code: "INSTRUCTION_REVISION_REQUIRED" } });
+    expect(await fs.readFile(path.join(root, "NEXT.md"), "utf8")).toBe("new configured entry");
+    expect(upsertAgentInstructionsFileSchema.safeParse({ path: entryFile, content: "bad", responsibleUserId: userId }).success).toBe(false);
+  });
+});
diff --git a/server/src/__tests__/agent-instructions-routes.test.ts b/server/src/__tests__/agent-instructions-routes.test.ts
index 0a110b78025..5fdfc494d95 100644
--- a/server/src/__tests__/agent-instructions-routes.test.ts
+++ b/server/src/__tests__/agent-instructions-routes.test.ts
@@ -24,6 +24,9 @@ const mockAgentInstructionsService = vi.hoisted(() => ({
   materializeManagedBundle: vi.fn(),
 }));
 
+const mockInstructionRevisions = vi.hoisted(() => ({ readCurrent: vi.fn(), commit: vi.fn(), restore: vi.fn(), history: vi.fn(), readRevision: vi.fn(), diff: vi.fn(), materializeCurrent: vi.fn() }));
+vi.mock("../services/agent-instruction-revisions.js", () => ({ agentInstructionRevisionService: () => mockInstructionRevisions }));
+
 const mockAccessService = vi.hoisted(() => ({
   canUser: vi.fn(),
   decide: vi.fn(),
@@ -202,6 +205,8 @@ describe("agent instructions bundle routes", () => {
     vi.doUnmock("../middleware/index.js");
     registerModuleMocks();
     vi.clearAllMocks();
+    mockInstructionRevisions.readCurrent.mockResolvedValue(null);
+    mockInstructionRevisions.commit.mockResolvedValue({ revision: { id: "33333333-3333-4333-8333-333333333333", entryFile: "AGENTS.md", byteLength: 18 }, content: "# Updated Agent\n", changed: true, materialization: "current" });
     mockBuiltInAgentService.ensureCompanyDefaultAgentGrants.mockResolvedValue(0);
     mockSyncInstructionsBundleConfigFromFilePath.mockImplementation((_agent, config) => config);
     mockFindServerAdapter.mockImplementation((_type: string) => ({ type: _type }));
@@ -484,7 +489,7 @@ describe("agent instructions bundle routes", () => {
     expect(mockAgentService.create).not.toHaveBeenCalled();
   });
 
-  it("denies non-privileged agents from reading peer instructions bundles", async () => {
+  it("denies instruction reads when the visibility policy denies access", async () => {
     mockAgentService.getById.mockImplementation(async (id: string) => {
       if (id === "agent-reader") {
         return {
@@ -516,7 +521,7 @@ describe("agent instructions bundle routes", () => {
     expect(res.status, JSON.stringify(res.body)).toBe(403);
     expect(res.body.error).toContain("Missing permission");
     expect(mockAccessService.decide).toHaveBeenCalledWith(expect.objectContaining({
-      action: "agent_config:read",
+      action: "agent:read",
       resource: {
         type: "agent",
         companyId: "company-1",
@@ -575,7 +580,7 @@ describe("agent instructions bundle routes", () => {
 
     expect(res.status, JSON.stringify(res.body)).toBe(200);
     expect(mockAccessService.decide).toHaveBeenCalledWith(expect.objectContaining({
-      action: "agent_config:read",
+      action: "agent:read",
       resource: {
         type: "agent",
         companyId: "company-1",
@@ -588,34 +593,52 @@ describe("agent instructions bundle routes", () => {
     );
   });
 
-  it("writes a bundle file and persists compatibility config", async () => {
+  it("commits entry bytes through the canonical service with the authenticated actor", async () => {
     const res = await requestApp(await createApp(), (baseUrl) => request(baseUrl)
       .put("/api/agents/11111111-1111-4111-8111-111111111111/instructions-bundle/file?companyId=company-1")
-      .send({
-        path: "AGENTS.md",
-        content: "# Updated Agent\n",
-        clearLegacyPromptTemplate: true,
-      }));
-
+      .send({ path: "AGENTS.md", content: "# Updated Agent\n", baseRevisionId: null }));
     expect(res.status, JSON.stringify(res.body)).toBe(200);
-    expect(mockAgentInstructionsService.writeFile).toHaveBeenCalledWith(
-      expect.objectContaining({ id: "11111111-1111-4111-8111-111111111111" }),
-      "AGENTS.md",
-      "# Updated Agent\n",
-      { clearLegacyPromptTemplate: true },
-    );
-    expect(mockAgentService.update).toHaveBeenCalledWith(
-      "11111111-1111-4111-8111-111111111111",
-      expect.objectContaining({
-        adapterConfig: expect.objectContaining({
-          instructionsBundleMode: "managed",
-          instructionsRootPath: "/tmp/agent-1",
-          instructionsEntryFile: "AGENTS.md",
-          instructionsFilePath: "/tmp/agent-1/AGENTS.md",
-        }),
-      }),
-      expect.any(Object),
-    );
+    expect(mockInstructionRevisions.commit).toHaveBeenCalledWith(expect.objectContaining({
+      agentId: "11111111-1111-4111-8111-111111111111", entryFile: "AGENTS.md", content: "# Updated Agent\n", baseRevisionId: null, source: "board",
+    }), expect.objectContaining({ type: "board" }));
+    expect(mockAgentInstructionsService.writeFile).not.toHaveBeenCalled();
+    expect(res.body.receipt.revision.id).toBe("33333333-3333-4333-8333-333333333333");
+  });
+
+  it("returns committed entry content independently of its disk copy", async () => {
+    mockInstructionRevisions.readCurrent.mockResolvedValue({ revision: { id: "33333333-3333-4333-8333-333333333333", entryFile: "AGENTS.md", byteLength: 9 }, content: "committed" });
+    const res = await requestApp(await createApp(), (baseUrl) => request(baseUrl)
+      .get("/api/agents/11111111-1111-4111-8111-111111111111/instructions-bundle/file?path=AGENTS.md"));
+    expect(res.status).toBe(200);
+    expect(res.body.content).toBe("committed");
+    expect(res.body.revision.id).toBe("33333333-3333-4333-8333-333333333333");
+    expect(mockAgentInstructionsService.readFile).not.toHaveBeenCalled();
+  });
+
+  it("exposes scoped history, diff and restore with the server actor", async () => {
+    const app = await createApp();
+    const revisionId = "33333333-3333-4333-8333-333333333333";
+    const baseRevisionId = "44444444-4444-4444-8444-444444444444";
+    const prefix = "/api/agents/11111111-1111-4111-8111-111111111111/instructions-bundle";
+    mockInstructionRevisions.history.mockResolvedValue({ revisions: [], nextCursor: null });
+    mockInstructionRevisions.diff.mockResolvedValue({ removed: "old", added: "new" });
+    mockInstructionRevisions.restore.mockResolvedValue({ revision: { id: revisionId, entryFile: "AGENTS.md", byteLength: 3 }, content: "old", changed: true, materialization: "current" });
+    expect((await requestApp(app, (url) => request(url).get(`${prefix}/history?path=AGENTS.md`))).status).toBe(200);
+    expect((await requestApp(app, (url) => request(url).get(`${prefix}/diff?path=AGENTS.md&from=${revisionId}&to=${baseRevisionId}`))).status).toBe(200);
+    const restored = await requestApp(app, (url) => request(url).post(`${prefix}/restore`).send({ path: "AGENTS.md", revisionId, baseRevisionId }));
+    expect(restored.status).toBe(200);
+    expect(restored.body.receipt.changed).toBe(true);
+    expect(mockInstructionRevisions.restore).toHaveBeenCalledWith({ companyId: "company-1", agentId: "11111111-1111-4111-8111-111111111111", entryFile: "AGENTS.md", revisionId, baseRevisionId }, expect.objectContaining({ type: "board", userId: "local-board" }));
+  });
+
+  it("requires a base revision and rejects client-supplied responsible identity", async () => {
+    const app = await createApp();
+    for (const body of [ { path: "AGENTS.md", content: "stale" }, { path: "AGENTS.md", content: "forged", baseRevisionId: null, responsibleUserId: "forged" } ]) {
+      const res = await requestApp(app, (baseUrl) => request(baseUrl)
+        .put("/api/agents/11111111-1111-4111-8111-111111111111/instructions-bundle/file").send(body));
+      expect([400, 422]).toContain(res.status);
+    }
+    expect(mockInstructionRevisions.commit).not.toHaveBeenCalled();
   });
 
   it("preserves managed instructions config when switching adapters", async () => {
diff --git a/server/src/__tests__/agent-instructions-service.test.ts b/server/src/__tests__/agent-instructions-service.test.ts
index 2dc4719d1a8..948e55d47e7 100644
--- a/server/src/__tests__/agent-instructions-service.test.ts
+++ b/server/src/__tests__/agent-instructions-service.test.ts
@@ -53,7 +53,7 @@ describe("agent instructions service", () => {
     await fs.mkdir(path.join(externalRoot, "docs"), { recursive: true });
     await fs.writeFile(path.join(externalRoot, "docs", "TOOLS.md"), "## Tools\n", "utf8");
 
-    const svc = agentInstructionsService();
+    const svc = agentInstructionsService({ select: () => ({ from: () => ({ where: async () => [] }) }) } as never);
     const agent = makeAgent({
       instructionsBundleMode: "external",
       instructionsRootPath: externalRoot,
@@ -250,11 +250,10 @@ describe("agent instructions service", () => {
 
     expect(bundle.mode).toBe("managed");
     expect(bundle.rootPath).toBe(managedRoot);
-    expect(bundle.entryFile).toBe("AGENTS.md");
+    expect(bundle.entryFile).toBe("docs/MISSING.md");
     expect(bundle.files.map((file) => file.path)).toEqual(["AGENTS.md"]);
     expect(bundle.warnings).toEqual([
       `Recovered managed instructions from disk at ${managedRoot}; ignoring stale configured root ${staleRoot}.`,
-      "Recovered managed instructions entry file from disk as AGENTS.md; previous entry docs/MISSING.md was missing.",
     ]);
     expect(exported.files).toEqual({ "AGENTS.md": "# Managed Agent\n" });
   });
@@ -293,8 +292,8 @@ describe("agent instructions service", () => {
     expect(result.adapterConfig).toMatchObject({
       instructionsBundleMode: "managed",
       instructionsRootPath: managedRoot,
-      instructionsEntryFile: "AGENTS.md",
-      instructionsFilePath: path.join(managedRoot, "AGENTS.md"),
+      instructionsEntryFile: "docs/MISSING.md",
+      instructionsFilePath: path.join(managedRoot, "docs/MISSING.md"),
     });
     await expect(fs.readFile(path.join(managedRoot, "docs", "TOOLS.md"), "utf8")).resolves.toBe("## Tools\n");
   });
@@ -334,8 +333,8 @@ describe("agent instructions service", () => {
     expect(result.adapterConfig).toMatchObject({
       instructionsBundleMode: "managed",
       instructionsRootPath: managedRoot,
-      instructionsEntryFile: "AGENTS.md",
-      instructionsFilePath: path.join(managedRoot, "AGENTS.md"),
+      instructionsEntryFile: "docs/MISSING.md",
+      instructionsFilePath: path.join(managedRoot, "docs/MISSING.md"),
     });
     await expect(fs.stat(path.join(managedRoot, "docs", "TOOLS.md"))).rejects.toThrow();
     expect(result.bundle.files.map((file) => file.path)).toEqual(["AGENTS.md"]);
@@ -373,11 +372,10 @@ describe("agent instructions service", () => {
 
     expect(bundle.mode).toBe("managed");
     expect(bundle.rootPath).toBe(managedRoot);
-    expect(bundle.entryFile).toBe("AGENTS.md");
+    expect(bundle.entryFile).toBe("docs/MISSING.md");
     expect(bundle.files.map((file) => file.path)).toEqual(["AGENTS.md"]);
     expect(bundle.warnings).toEqual([
       `Recovered managed instructions from disk at ${managedRoot}; ignoring stale configured root ${staleRoot}.`,
-      "Recovered managed instructions entry file from disk as AGENTS.md; previous entry docs/MISSING.md was missing.",
     ]);
     expect(exported.files).toEqual({ "AGENTS.md": "# Managed Agent\n" });
   });
diff --git a/server/src/__tests__/built-in-agent-routes.test.ts b/server/src/__tests__/built-in-agent-routes.test.ts
index acae6704dc3..e51166f2ba4 100644
--- a/server/src/__tests__/built-in-agent-routes.test.ts
+++ b/server/src/__tests__/built-in-agent-routes.test.ts
@@ -412,7 +412,7 @@ describe("built-in agent routes", () => {
       .send({});
 
     expect(res.status, JSON.stringify(res.body)).toBe(200);
-    expect(mockBuiltInAgentService.reset).toHaveBeenCalledWith(companyId, "briefs", {});
+    expect(mockBuiltInAgentService.reset).toHaveBeenCalledWith(companyId, "briefs", {}, expect.objectContaining({ type: "agent", agentId: "manager-agent" }));
     expect(mockLogActivity).toHaveBeenCalledWith(expect.anything(), expect.objectContaining({
       companyId,
       actorType: "agent",
diff --git a/server/src/__tests__/built-in-agents.test.ts b/server/src/__tests__/built-in-agents.test.ts
index 8f3abf3972d..36f4a349e6b 100644
--- a/server/src/__tests__/built-in-agents.test.ts
+++ b/server/src/__tests__/built-in-agents.test.ts
@@ -27,6 +27,7 @@ import {
   getEmbeddedPostgresTestSupport,
   startEmbeddedPostgresTestDatabase,
 } from "./helpers/embedded-postgres.js";
+import { agentInstructionRevisionService } from "../services/agent-instruction-revisions.js";
 import { agentInstructionsService } from "../services/agent-instructions.ts";
 import { agentService } from "../services/agents.ts";
 import { approvalService } from "../services/approvals.ts";
@@ -116,6 +117,16 @@ describe("built-in agent asset loading", () => {
 describeEmbeddedPostgres("built-in agents", () => {
   let db!: ReturnType<typeof createDb>;
   let tempDb: Awaited<ReturnType<typeof startEmbeddedPostgresTestDatabase>> | null = null;
+  const instructionOperator = { type: "board", userId: "local-board", source: "local_implicit" } as const;
+  async function writeInstructionEntry(agent: { id: string; companyId: string }, entryFile: string, content: string) {
+    const service = agentInstructionRevisionService(db);
+    const target = { companyId: agent.companyId, agentId: agent.id };
+    const baseline = await service.readCurrent(target, instructionOperator);
+    await service.commit({ ...target, entryFile, content, baseRevisionId: baseline?.revision.id ?? null, source: "board" }, instructionOperator);
+    const refreshed = await agentService(db).getById(agent.id);
+    return { adapterConfig: refreshed!.adapterConfig };
+  }
+
 
   beforeAll(async () => {
     tempDb = await startEmbeddedPostgresTestDatabase("paperclip-built-in-agents-");
@@ -553,7 +564,7 @@ describeEmbeddedPostgres("built-in agents", () => {
       capabilities: "Custom purpose",
     });
 
-    const reset = await builtIns.reset(companyId, "briefs");
+    const reset = await builtIns.reset(companyId, "briefs", {}, instructionOperator);
 
     expect(reset).toMatchObject({
       status: "ready",
@@ -801,7 +812,7 @@ describeEmbeddedPostgres("built-in agents", () => {
     const created = await builtIns.ensure(companyId, "reflection-coach");
     const instructions = agentInstructionsService();
 
-    await instructions.writeFile(created.agent!, "AGENTS.md", "# Custom Reflection Coach\n\nOperator edit.\n");
+    await writeInstructionEntry(created.agent!, "AGENTS.md", "# Custom Reflection Coach\n\nOperator edit.\n");
 
     const reconciled = await builtIns.ensure(companyId, "reflection-coach");
     const drift = reconciled.resources.find((resource) => resource.resourceKind === "instructions");
@@ -815,7 +826,7 @@ describeEmbeddedPostgres("built-in agents", () => {
       content: "# Custom Reflection Coach\n\nOperator edit.\n",
     });
 
-    const reset = await builtIns.reset(companyId, "reflection-coach");
+    const reset = await builtIns.reset(companyId, "reflection-coach", {}, instructionOperator);
     expect(reset.resources.find((resource) => resource.resourceKind === "instructions")).toMatchObject({
       stockStatus: "stock_current",
       resetAvailable: false,
@@ -823,6 +834,13 @@ describeEmbeddedPostgres("built-in agents", () => {
     const resetFile = await instructions.readFile(reset.agent!, "AGENTS.md");
     expect(resetFile.content).toContain("Reflection Coach");
     expect(resetFile.content).not.toContain("Operator edit.");
+    const revisions = agentInstructionRevisionService(db);
+    const target = { companyId, agentId: created.agent!.id, entryFile: "AGENTS.md" };
+    const history = await revisions.history(target, instructionOperator);
+    expect(history.revisions).toHaveLength(3);
+    expect(history.revisions[0]).toMatchObject({ source: "board", actorUserId: "local-board" });
+    const previous = await revisions.readRevision({ ...target, revisionId: history.revisions[1]!.id }, instructionOperator);
+    expect(previous.content).toBe("# Custom Reflection Coach\n\nOperator edit.\n");
   });
 
   it("blocks deleting a built-in agent", async () => {
@@ -1270,7 +1288,7 @@ describeEmbeddedPostgres("built-in agents", () => {
     const created = await builtIns.ensure(companyId, "summarizer");
     const instructions = agentInstructionsService();
 
-    await instructions.writeFile(created.agent!, "AGENTS.md", "# Custom Summarizer\n\nOperator edit.\n");
+    await writeInstructionEntry(created.agent!, "AGENTS.md", "# Custom Summarizer\n\nOperator edit.\n");
 
     const reconciled = await builtIns.ensure(companyId, "summarizer");
     expect(reconciled.resources.find((resource) => resource.resourceKind === "instructions")).toMatchObject({
@@ -1279,7 +1297,7 @@ describeEmbeddedPostgres("built-in agents", () => {
       changedFiles: ["AGENTS.md"],
     });
 
-    const reset = await builtIns.reset(companyId, "summarizer");
+    const reset = await builtIns.reset(companyId, "summarizer", {}, instructionOperator);
     expect(reset.resources.find((resource) => resource.resourceKind === "instructions")).toMatchObject({
       stockStatus: "stock_current",
       resetAvailable: false,
@@ -1419,7 +1437,7 @@ describeEmbeddedPostgres("built-in agents", () => {
     const coach = created.agent!;
     const instructionsSvc = agentInstructionsService();
     const originalInstructions = "# Target Coder\n\nWork from the assigned issue.\n";
-    const prepared = await instructionsSvc.writeFile(target, "AGENTS.md", originalInstructions);
+    const prepared = await writeInstructionEntry(target, "AGENTS.md", originalInstructions);
     let persistedTarget = (await agentsSvc.update(target.id, { adapterConfig: prepared.adapterConfig }))!;
 
     const interactionsSvc = issueThreadInteractionService(db);
@@ -1431,7 +1449,7 @@ describeEmbeddedPostgres("built-in agents", () => {
       if (interaction?.kind !== "request_confirmation" || interaction.status !== "accepted") {
         return false;
       }
-      const written = await instructionsSvc.writeFile(persistedTarget, "AGENTS.md", input.nextInstructions);
+      const written = await writeInstructionEntry(persistedTarget, "AGENTS.md", input.nextInstructions);
       persistedTarget = (await agentsSvc.update(persistedTarget.id, { adapterConfig: written.adapterConfig }))!;
       return true;
     };
@@ -1568,7 +1586,7 @@ describeEmbeddedPostgres("built-in agents", () => {
     const agent = created.agent!;
 
     const instructionsSvc = agentInstructionsService();
-    await instructionsSvc.writeFile(agent, "AGENTS.md", "# Custom Reflection Coach\n\nDo not overwrite me.\n");
+    await writeInstructionEntry(agent, "AGENTS.md", "# Custom Reflection Coach\n\nDo not overwrite me.\n");
     await db
       .update(companySkills)
       .set({ markdown: "---\nname: reflection-coach\n---\n\n# Custom skill\n" })
@@ -1597,7 +1615,7 @@ describeEmbeddedPostgres("built-in agents", () => {
 
     const reset = await builtInAgentService(db).reset(companyId, "reflection-coach", {
       resources: ["instructions", "routine"],
-    });
+    }, instructionOperator);
     expect(reset.resources.find((resource) => resource.resourceKind === "instructions")).toMatchObject({
       stockStatus: "stock_current",
       resetAvailable: false,
diff --git a/server/src/routes/agents.ts b/server/src/routes/agents.ts
index 2efcc764571..1d29fa758ad 100644
--- a/server/src/routes/agents.ts
+++ b/server/src/routes/agents.ts
@@ -38,6 +38,7 @@ import {
   type AgentSkillSnapshot,
   type InstanceSchedulerHeartbeatAgent,
   upsertAgentInstructionsFileSchema,
+  restoreAgentInstructionSchema,
   updateAgentInstructionsBundleSchema,
   updateAgentPermissionsSchema,
   updateAgentInstructionsPathSchema,
@@ -63,7 +64,9 @@ import {
 import { trackAgentCreated } from "@paperclipai/shared/telemetry";
 import { validate } from "../middleware/validate.js";
 import { inheritNativeRunnerAdapterConfig } from "../services/native-runtime/native-agent-runtime-inheritance.js";
-import { agentInstructionsBundleMode } from "../services/agent-instructions.js";
+import { agentInstructionRevisionService } from "../services/agent-instruction-revisions.js";
+import { instructionPath } from "../services/agent-instruction-files.js";
+import { agentInstructionsBundleMode, deriveBundleState } from "../services/agent-instructions.js";
 import {
   agentService,
   agentInstructionsService,
@@ -724,7 +727,15 @@ export function agentRoutes(
   const recovery = recoveryService(db, { enqueueWakeup: heartbeat.wakeup });
   const issueApprovalsSvc = issueApprovalService(db);
   const secretsSvc = secretService(db);
-  const instructions = agentInstructionsService();
+  const instructions = agentInstructionsService(db);
+  const instructionRevisions = agentInstructionRevisionService(db);
+  function instructionFileDetail(snapshot: import("@paperclipai/shared").AgentInstructionSnapshot,
+    receipt?: import("@paperclipai/shared").AgentInstructionCommitReceipt) {
+    const path = snapshot.revision.entryFile;
+    return { path, content: snapshot.content, size: snapshot.revision.byteLength, revision: snapshot.revision, receipt,
+      language: path.toLowerCase().endsWith(".md") ? "markdown" : "text", markdown: path.toLowerCase().endsWith(".md"),
+      isEntryFile: true, editable: true, deprecated: false, virtual: false };
+  }
   const companySkills = companySkillService(db);
   const workspaceOperations = workspaceOperationService(db);
   const instanceSettings = instanceSettingsService(db);
@@ -5067,8 +5078,21 @@ export function agentRoutes(
     const id = req.params.id as string;
     const existing = await getAccessibleResource(req, res, svc.getById(id), "Agent not found");
     if (!existing) return;
-    await assertCanReadAgent(req, existing);
+    const readDecision = await access.decide({ actor: req.actor, action: "agent:read", resource: { type: "agent", companyId: existing.companyId, agentId: existing.id } });
+    if (!readDecision.allowed) throw forbidden(readDecision.explanation, authorizationDeniedDetails(readDecision));
     assertExternalInstructionsAdmin(req, existing);
+    if (agentInstructionsBundleMode(existing) !== "external") {
+      const target = { companyId: existing.companyId, agentId: existing.id };
+      const current = await instructionRevisions.readCurrent(target, req.actor);
+      if (current) {
+        try { await instructionRevisions.materializeCurrent(target); }
+        catch (error) {
+          const bundle = await instructions.getBundle(existing);
+          bundle.warnings.push(`Saved instruction revision needs materialization: ${error instanceof Error ? error.message : String(error)}`);
+          res.json(bundle); return;
+        }
+      }
+    }
     res.json(await instructions.getBundle(existing));
   });
 
@@ -5124,7 +5148,8 @@ export function agentRoutes(
     const id = req.params.id as string;
     const existing = await getAccessibleResource(req, res, svc.getById(id), "Agent not found");
     if (!existing) return;
-    await assertCanReadAgent(req, existing);
+    const readDecision = await access.decide({ actor: req.actor, action: "agent:read", resource: { type: "agent", companyId: existing.companyId, agentId: existing.id } });
+    if (!readDecision.allowed) throw forbidden(readDecision.explanation, authorizationDeniedDetails(readDecision));
     assertExternalInstructionsAdmin(req, existing);
 
     const relativePath = typeof req.query.path === "string" ? req.query.path : "";
@@ -5133,6 +5158,10 @@ export function agentRoutes(
       return;
     }
 
+    if (agentInstructionsBundleMode(existing) !== "external" && instructionPath(relativePath) === deriveBundleState(existing).entryFile) {
+      const snapshot = await instructionRevisions.readCurrent({ companyId: existing.companyId, agentId: existing.id }, req.actor);
+      if (snapshot) { res.json(instructionFileDetail(snapshot)); return; }
+    }
     res.json(await instructions.readFile(existing, relativePath));
   });
 
@@ -5140,6 +5169,27 @@ export function agentRoutes(
     const id = req.params.id as string;
     const existing = await getAccessibleResource(req, res, svc.getById(id), "Agent not found");
     if (!existing) return;
+    const entryFile = deriveBundleState(existing).entryFile;
+    if (instructionPath(req.body.path) === entryFile) {
+      assertExternalInstructionsAdmin(req, existing);
+      if (req.body.baseRevisionId === undefined) throw unprocessable("Read the entry and supply baseRevisionId (null for a new entry)", { code: "INSTRUCTION_BASE_REQUIRED" });
+      // Clearing legacy prompt configuration remains a protected config change.
+      if (req.body.clearLegacyPromptTemplate) await assertCanManageInstructionsPath(req, existing);
+      const receipt = await instructionRevisions.commit({ companyId: existing.companyId, agentId: existing.id,
+        entryFile, content: req.body.content, baseRevisionId: req.body.baseRevisionId,
+        source: req.actor.type === "board" ? "board" : "api" }, req.actor);
+      if (req.body.clearLegacyPromptTemplate) {
+        const fresh = await svc.getById(existing.id);
+        if (fresh) {
+          const adapterConfig = { ...asRecord(fresh.adapterConfig) };
+          delete adapterConfig.promptTemplate;
+          delete adapterConfig.bootstrapPromptTemplate;
+          await svc.update(existing.id, { adapterConfig });
+        }
+      }
+      res.json(instructionFileDetail(receipt, receipt));
+      return;
+    }
     await assertCanManageInstructionsPath(req, existing);
     assertExternalInstructionsAdmin(req, existing);
 
@@ -5184,6 +5234,43 @@ export function agentRoutes(
     res.json(result.file);
   });
 
+  router.get("/agents/:id/instructions-bundle/history", async (req, res) => {
+    const existing = await getAccessibleResource(req, res, svc.getById(req.params.id as string), "Agent not found");
+    if (!existing) return;
+    assertExternalInstructionsAdmin(req, existing);
+    const entryFile = typeof req.query.path === "string" ? req.query.path : deriveBundleState(existing).entryFile;
+    const cursor = typeof req.query.cursor === "string" ? req.query.cursor : undefined;
+    if (cursor && !isUuidLike(cursor)) throw unprocessable("Invalid history cursor");
+    res.json(await instructionRevisions.history({ companyId: existing.companyId, agentId: existing.id, entryFile, cursor }, req.actor));
+  });
+  router.get("/agents/:id/instructions-bundle/revision/:revisionId", async (req, res) => {
+    const existing = await getAccessibleResource(req, res, svc.getById(req.params.id as string), "Agent not found");
+    if (!existing) return;
+    assertExternalInstructionsAdmin(req, existing);
+    const revisionId = req.params.revisionId as string;
+    if (!isUuidLike(revisionId)) throw unprocessable("Invalid instruction revision id");
+    const entryFile = typeof req.query.path === "string" ? req.query.path : deriveBundleState(existing).entryFile;
+    res.json(await instructionRevisions.readRevision({ companyId: existing.companyId, agentId: existing.id, entryFile, revisionId }, req.actor));
+  });
+  router.get("/agents/:id/instructions-bundle/diff", async (req, res) => {
+    const existing = await getAccessibleResource(req, res, svc.getById(req.params.id as string), "Agent not found");
+    if (!existing) return;
+    assertExternalInstructionsAdmin(req, existing);
+    const fromRevisionId = typeof req.query.from === "string" ? req.query.from : "";
+    const toRevisionId = typeof req.query.to === "string" ? req.query.to : "";
+    if (!isUuidLike(fromRevisionId) || !isUuidLike(toRevisionId)) throw unprocessable("Provide valid from and to revision ids");
+    const entryFile = typeof req.query.path === "string" ? req.query.path : deriveBundleState(existing).entryFile;
+    res.json(await instructionRevisions.diff({ companyId: existing.companyId, agentId: existing.id, entryFile, fromRevisionId, toRevisionId }, req.actor));
+  });
+  router.post("/agents/:id/instructions-bundle/restore", validate(restoreAgentInstructionSchema), async (req, res) => {
+    const existing = await getAccessibleResource(req, res, svc.getById(req.params.id as string), "Agent not found");
+    if (!existing) return;
+    assertExternalInstructionsAdmin(req, existing);
+    const receipt = await instructionRevisions.restore({ companyId: existing.companyId, agentId: existing.id,
+      entryFile: req.body.path, baseRevisionId: req.body.baseRevisionId, revisionId: req.body.revisionId }, req.actor);
+    res.json(instructionFileDetail(receipt, receipt));
+  });
+
   router.delete("/agents/:id/instructions-bundle/file", async (req, res) => {
     const id = req.params.id as string;
     const existing = await getAccessibleResource(req, res, svc.getById(id), "Agent not found");
diff --git a/server/src/routes/built-in-agents.ts b/server/src/routes/built-in-agents.ts
index 9c16ba6f53b..c881ae9c93f 100644
--- a/server/src/routes/built-in-agents.ts
+++ b/server/src/routes/built-in-agents.ts
@@ -217,7 +217,7 @@ export function builtInAgentRoutes(db: Db) {
     const key = req.params.key as string;
     await assertBuiltInAgentsEnabled();
     await assertCanProvisionBuiltInAgents(req, companyId);
-    const state = await svc.reset(companyId, key, req.body);
+    const state = await svc.reset(companyId, key, req.body, req.actor);
     await logBuiltInAgentMutation(req, {
       companyId,
       action: "built_in_agent.reset",
diff --git a/server/src/routes/openapi.ts b/server/src/routes/openapi.ts
index 439262a6fce..df4dfbe4632 100644
--- a/server/src/routes/openapi.ts
+++ b/server/src/routes/openapi.ts
@@ -27,6 +27,7 @@ import {
   updateAgentInstructionsPathSchema,
   updateAgentInstructionsBundleSchema,
   upsertAgentInstructionsFileSchema,
+  restoreAgentInstructionSchema,
   createAgentKeySchema,
   builtInAgentEmptyMutationSchema,
   builtInAgentProvisionSchema,
@@ -3471,6 +3472,19 @@ registry.registerPath({
   responses: { 200: r.ok(), 400: r.badRequest, 401: r.unauthorized },
 });
 
+for (const operation of [
+  { suffix: "history", summary: "List immutable instruction revisions", query: z.object({ path: z.string().optional(), cursor: z.string().uuid().optional() }) },
+  { suffix: "revision/{revisionId}", summary: "Read exact instruction content at a revision", query: z.object({ path: z.string().optional() }) },
+  { suffix: "diff", summary: "Compare instruction revisions (exact common prefix, removed, added, suffix)", query: z.object({ path: z.string().optional(), from: z.string().uuid(), to: z.string().uuid() }) },
+]) {
+  registry.registerPath({ method: "get", path: `/api/agents/{id}/instructions-bundle/${operation.suffix}`, tags: ["agents"], summary: operation.summary,
+    request: { params: operation.suffix.includes("revisionId") ? z.object({ id: z.string(), revisionId: z.string().uuid() }) : z.object({ id: z.string() }), query: operation.query },
+    responses: { 200: r.ok(), 401: r.unauthorized, 403: r.forbidden, 404: r.notFound } });
+}
+registry.registerPath({ method: "post", path: "/api/agents/{id}/instructions-bundle/restore", tags: ["agents"], summary: "Restore instruction content as a new revision with compare-and-swap",
+  request: { params: z.object({ id: z.string() }), body: jsonBody(restoreAgentInstructionSchema) },
+  responses: { 200: r.ok(), 401: r.unauthorized, 403: r.forbidden, 404: r.notFound, 409: r.conflict } });
+
 registry.registerPath({
   method: "delete",
   path: "/api/agents/{id}/instructions-bundle/file",
diff --git a/server/src/services/agent-instruction-authorization.ts b/server/src/services/agent-instruction-authorization.ts
new file mode 100644
index 00000000000..21798941f3f
--- /dev/null
+++ b/server/src/services/agent-instruction-authorization.ts
@@ -0,0 +1,175 @@
+import { and, eq, isNull } from "drizzle-orm";
+import {
+  agentApiKeys,
+  authUsers,
+  companyMemberships,
+  heartbeatRuns,
+  runIdentityContexts,
+  type Db,
+} from "@paperclipai/db";
+import { forbidden } from "../errors.js";
+import {
+  authorizationService,
+  authorizationDeniedDetails,
+  type AuthorizationActor,
+} from "./authorization.js";
+import {
+  agentInstructionsChangeTargetKey,
+  changeConsentGateService,
+} from "./change-consent-gate.js";
+
+type Connection = Db | Parameters<Parameters<Db["transaction"]>[0]>[0];
+
+/** Accept ONLY a server-authenticated actor, never request/tool JSON. Rebind run/key provenance on every call. */
+export async function resolveInstructionActor(
+  db: Connection,
+  actor: AuthorizationActor,
+): Promise<AuthorizationActor> {
+  if (actor.type === "board") {
+    if (!actor.userId)
+      throw forbidden("Instruction edits require an authenticated user");
+    // Discard caller membership caches so revoked access is observed.
+    return {
+      type: "board",
+      userId: actor.userId,
+      source: actor.source,
+      ignoreInstanceAdmin: actor.ignoreInstanceAdmin,
+    };
+  }
+  if (actor.type !== "agent" || !actor.agentId || !actor.companyId)
+    throw forbidden("Instruction identity is missing");
+  let responsibleUserId: string | null = null;
+  let keyScope = actor.keyScope;
+  if (actor.keyId) {
+    const [key] = await db
+      .select()
+      .from(agentApiKeys)
+      .where(
+        and(
+          eq(agentApiKeys.id, actor.keyId),
+          eq(agentApiKeys.companyId, actor.companyId),
+          eq(agentApiKeys.agentId, actor.agentId),
+          isNull(agentApiKeys.revokedAt),
+        ),
+      );
+    if (!key)
+      throw forbidden("Instruction API key is missing or revoked", {
+        code: "INSTRUCTION_IDENTITY_INVALID",
+      });
+    responsibleUserId = key.responsibleUserId;
+    keyScope = key.scopeConfig ?? undefined;
+  }
+  if (actor.runId) {
+    const [run] = await db
+      .select()
+      .from(heartbeatRuns)
+      .where(
+        and(
+          eq(heartbeatRuns.id, actor.runId),
+          eq(heartbeatRuns.companyId, actor.companyId),
+          eq(heartbeatRuns.agentId, actor.agentId),
+        ),
+      );
+    if (!run)
+      throw forbidden("Instruction run identity does not match", {
+        code: "INSTRUCTION_IDENTITY_INVALID",
+      });
+    if (actor.keyId && responsibleUserId !== run.responsibleUserId)
+      throw forbidden("Key and run responsible identity do not match", {
+        code: "INSTRUCTION_IDENTITY_INVALID",
+      });
+    responsibleUserId = run.responsibleUserId;
+    if (run.activeIdentityContextId) {
+      const [context] = await db
+        .select()
+        .from(runIdentityContexts)
+        .where(
+          and(
+            eq(runIdentityContexts.id, run.activeIdentityContextId),
+            eq(runIdentityContexts.runId, run.id),
+            eq(runIdentityContexts.companyId, run.companyId),
+            eq(runIdentityContexts.status, "accepted"),
+          ),
+        );
+      if (!context)
+        throw forbidden("Instruction run identity is unavailable", {
+          code: "INSTRUCTION_IDENTITY_INVALID",
+        });
+      responsibleUserId = context.responsibleUserId;
+    }
+  }
+  if (
+    !responsibleUserId ||
+    (actor.onBehalfOfUserId && actor.onBehalfOfUserId !== responsibleUserId)
+  ) {
+    throw forbidden("A current server-bound responsible user is required", {
+      code: "INSTRUCTION_IDENTITY_INVALID",
+    });
+  }
+  const [membership] = await db
+    .select({ userId: authUsers.id })
+    .from(companyMemberships)
+    .innerJoin(authUsers, eq(authUsers.id, companyMemberships.principalId))
+    .where(
+      and(
+        eq(companyMemberships.companyId, actor.companyId),
+        eq(companyMemberships.principalType, "user"),
+        eq(companyMemberships.principalId, responsibleUserId),
+        eq(companyMemberships.status, "active"),
+      ),
+    );
+  if (!membership)
+    throw forbidden("The responsible user is unavailable in this company", {
+      code: "RESPONSIBLE_USER_UNAVAILABLE",
+    });
+  return {
+    type: "agent",
+    agentId: actor.agentId,
+    companyId: actor.companyId,
+    runId: actor.runId,
+    keyId: actor.keyId,
+    keyScope,
+    source: actor.source,
+    onBehalfOfUserId: responsibleUserId,
+  };
+}
+
+/** Current target edit access + agent containment + protected-change consent, shared by all writers. */
+export async function authorizeInstructionCommit(
+  db: Connection,
+  actor: AuthorizationActor,
+  target: { companyId: string; id: string },
+) {
+  const bound = await resolveInstructionActor(db, actor);
+  const access = authorizationService(db);
+  const input = {
+    actor: bound,
+    action: "agent_instructions:update" as const,
+    resource: {
+      type: "agent" as const,
+      companyId: target.companyId,
+      agentId: target.id,
+    },
+    scope: { targetAgentId: target.id, requiresChangeGrant: true },
+  };
+  let decision = await access.decide(input);
+  if (
+    !decision.allowed &&
+    decision.reason === "deny_missing_consent" &&
+    bound.type === "agent"
+  ) {
+    await changeConsentGateService(db).assertConsented({
+      companyId: target.companyId,
+      actorAgentId: bound.agentId,
+      actorRunId: bound.runId,
+      targetKeys: [agentInstructionsChangeTargetKey(target.id)],
+    });
+    decision = await access.decide({
+      ...input,
+      scope: { ...input.scope, consentedChange: true },
+    });
+  }
+  if (!decision.allowed)
+    throw forbidden(decision.explanation, authorizationDeniedDetails(decision));
+  return bound;
+}
diff --git a/server/src/services/agent-instruction-files.ts b/server/src/services/agent-instruction-files.ts
new file mode 100644
index 00000000000..c839ec3ecab
--- /dev/null
+++ b/server/src/services/agent-instruction-files.ts
@@ -0,0 +1,149 @@
+import fs from "node:fs/promises";
+import { constants } from "node:fs";
+import path from "node:path";
+import { randomUUID } from "node:crypto";
+import { unprocessable } from "../errors.js";
+
+export const MAX_INSTRUCTION_BYTES = 1024 * 1024;
+export function instructionPath(value: string): string {
+  if (
+    !value ||
+    value.length > 512 ||
+    value.includes("\0") ||
+    value.includes("\\") ||
+    path.posix.isAbsolute(value) ||
+    /^[a-z]:/i.test(value) ||
+    value.split("/").some((part) => !part || part === "." || part === "..")
+  ) {
+    throw unprocessable("Use a relative instructions path without traversal", {
+      code: "INSTRUCTION_PATH_INVALID",
+    });
+  }
+  return value;
+}
+
+export function instructionBytes(content: string | Uint8Array): Buffer {
+  const byteLength =
+    typeof content === "string"
+      ? Buffer.byteLength(content, "utf8")
+      : content.byteLength;
+  if (byteLength > MAX_INSTRUCTION_BYTES) {
+    throw unprocessable("Instructions exceed the 1 MiB limit", {
+      code: "INSTRUCTION_CONTENT_INVALID",
+    });
+  }
+  const bytes =
+    typeof content === "string"
+      ? Buffer.from(content, "utf8")
+      : Buffer.from(content);
+  try {
+    // Preserve BOM; reject invalid UTF-8 and unpaired JS surrogates instead of replacing bytes.
+    const decoded = new TextDecoder("utf-8", {
+      fatal: true,
+      ignoreBOM: true,
+    }).decode(bytes);
+    if (typeof content === "string" && decoded !== content)
+      throw new Error("invalid Unicode");
+  } catch {
+    throw unprocessable("Instructions must be valid UTF-8", {
+      code: "INSTRUCTION_CONTENT_INVALID",
+    });
+  }
+  return bytes;
+}
+
+export async function assertInstructionPathSafe(
+  root: string,
+  entryFile: string,
+) {
+  instructionPath(entryFile);
+  const absolute = path.resolve(root, entryFile);
+  let current = path.parse(absolute).root;
+  const parts = absolute.slice(current.length).split(path.sep);
+  for (const [i, part] of parts.entries()) {
+    current = path.join(current, part);
+    const stat = await fs
+      .lstat(current)
+      .catch((error: NodeJS.ErrnoException) => {
+        if (error.code === "ENOENT") return null;
+        throw error;
+      });
+    if (!stat) continue;
+    if (
+      stat.isSymbolicLink() ||
+      (i < parts.length - 1 ? !stat.isDirectory() : !stat.isFile())
+    ) {
+      throw unprocessable(
+        "Instructions require regular files and directories without symlinks",
+        { code: "INSTRUCTION_PATH_INVALID" },
+      );
+    }
+  }
+  return absolute;
+}
+
+export async function readInstructionBytes(
+  root: string,
+  entryFile: string,
+): Promise<Buffer | null> {
+  const absolute = await assertInstructionPathSafe(root, entryFile);
+  const file = await fs
+    .open(absolute, constants.O_RDONLY | constants.O_NOFOLLOW)
+    .catch((error: NodeJS.ErrnoException) => {
+      if (error.code === "ENOENT") return null;
+      throw error;
+    });
+  if (!file) return null;
+  try {
+    const stat = await file.stat();
+    if (!stat.isFile() || stat.size > MAX_INSTRUCTION_BYTES) {
+      throw unprocessable(
+        "Instructions must be a regular UTF-8 file of at most 1 MiB",
+        { code: "INSTRUCTION_CONTENT_INVALID" },
+      );
+    }
+    const buffer = Buffer.alloc(MAX_INSTRUCTION_BYTES + 1);
+    let length = 0;
+    while (length < buffer.length) {
+      const result = await file.read(
+        buffer,
+        length,
+        buffer.length - length,
+        length,
+      );
+      if (result.bytesRead === 0) break;
+      length += result.bytesRead;
+    }
+    return instructionBytes(buffer.subarray(0, length));
+  } finally {
+    await file.close();
+  }
+}
+
+/** Call while holding the canonical agent lock. Never writes through a symlink. */
+export async function materializeInstructionBytes(
+  root: string,
+  entryFile: string,
+  bytes: Buffer,
+) {
+  const absolute = await assertInstructionPathSafe(root, entryFile);
+  await fs.mkdir(path.dirname(absolute), { recursive: true });
+  await assertInstructionPathSafe(root, entryFile);
+  const temporary = path.join(
+    path.dirname(absolute),
+    `.instruction-${randomUUID()}.tmp`,
+  );
+  try {
+    const file = await fs.open(temporary, "wx", 0o600);
+    try {
+      await file.writeFile(bytes);
+      await file.sync();
+    } finally {
+      await file.close();
+    }
+    await assertInstructionPathSafe(root, entryFile);
+    await fs.rename(temporary, absolute);
+  } finally {
+    await fs.rm(temporary, { force: true });
+  }
+}
diff --git a/server/src/services/agent-instruction-revisions.ts b/server/src/services/agent-instruction-revisions.ts
new file mode 100644
index 00000000000..a521e378e92
--- /dev/null
+++ b/server/src/services/agent-instruction-revisions.ts
@@ -0,0 +1,469 @@
+import { createHash } from "node:crypto";
+import { and, desc, eq, getTableColumns, lt, or, sql } from "drizzle-orm";
+import {
+  activityLog,
+  agents,
+  agentInstructionHeads as heads,
+  agentInstructionRevisions as revisions,
+  type Db,
+} from "@paperclipai/db";
+import type {
+  AgentInstructionCommitReceipt,
+  AgentInstructionDiff,
+  AgentInstructionHistory,
+  AgentInstructionSnapshot,
+  AgentInstructionSource,
+} from "@paperclipai/shared";
+import { conflict, forbidden, notFound, unprocessable } from "../errors.js";
+import {
+  agentInstructionsBundleMode,
+  deriveBundleState,
+  resolveManagedInstructionsRoot,
+} from "./agent-instructions.js";
+import {
+  instructionBytes,
+  instructionPath,
+  assertInstructionPathSafe,
+  readInstructionBytes,
+  materializeInstructionBytes,
+} from "./agent-instruction-files.js";
+import {
+  authorizeInstructionCommit,
+  resolveInstructionActor,
+} from "./agent-instruction-authorization.js";
+import {
+  authorizationService,
+  authorizationDeniedDetails,
+  type AuthorizationActor,
+} from "./authorization.js";
+
+type Tx = Parameters<Parameters<Db["transaction"]>[0]>[0];
+type Revision = typeof revisions.$inferSelect;
+const { contentBase64: _contentColumn, ...revisionMetadataColumns } =
+  getTableColumns(revisions);
+export type InstructionTarget = { companyId: string; agentId: string };
+export type InstructionCommitInput = InstructionTarget & {
+  entryFile: string;
+  content: string | Uint8Array;
+  baseRevisionId: string | null;
+  source: Exclude<AgentInstructionSource, "seed" | "restore">;
+};
+function metadata(row: Omit<Revision, "contentBase64">) {
+  const { createdAt, source, ...fields } = row;
+  return {
+    ...fields,
+    source: source as AgentInstructionSource,
+    createdAt: createdAt.toISOString(),
+  };
+}
+function snapshot(row: Revision): AgentInstructionSnapshot {
+  const { contentBase64, ...fields } = row;
+  return {
+    revision: metadata(fields),
+    content: Buffer.from(contentBase64, "base64").toString("utf8"),
+  };
+}
+function owner(target: InstructionTarget, entryFile: string) {
+  return and(
+    eq(revisions.companyId, target.companyId),
+    eq(revisions.agentId, target.agentId),
+    eq(revisions.entryFile, entryFile),
+  );
+}
+function headOwner(target: InstructionTarget, entryFile: string) {
+  return and(
+    eq(heads.companyId, target.companyId),
+    eq(heads.agentId, target.agentId),
+    eq(heads.entryFile, entryFile),
+  );
+}
+
+export function agentInstructionRevisionService(db: Db) {
+  async function lockTarget(
+    tx: Tx,
+    target: InstructionTarget,
+    actor?: AuthorizationActor,
+  ) {
+    if (actor?.type === "agent" && actor.companyId !== target.companyId)
+      throw notFound("Agent not found");
+    const [agent] = await tx
+      .select()
+      .from(agents)
+      .where(
+        and(
+          eq(agents.id, target.agentId),
+          eq(agents.companyId, target.companyId),
+        ),
+      )
+      .for("update");
+    if (!agent) throw notFound("Agent not found");
+    if (agentInstructionsBundleMode(agent) === "external") {
+      throw unprocessable(
+        "External host instructions do not support revision write-back. Ask an instance administrator to migrate this bundle to managed storage.",
+        { code: "INSTRUCTION_MANAGED_BUNDLE_REQUIRED" },
+      );
+    }
+    const state = deriveBundleState(agent);
+    const entryFile = instructionPath(state.entryFile);
+    return { agent, entryFile, root: resolveManagedInstructionsRoot(agent) };
+  }
+  async function authorizeRead(
+    tx: Tx,
+    actor: AuthorizationActor,
+    target: InstructionTarget,
+  ) {
+    const bound = await resolveInstructionActor(tx, actor);
+    const decision = await authorizationService(tx).decide({
+      actor: bound,
+      action: "agent:read",
+      resource: {
+        type: "agent",
+        companyId: target.companyId,
+        agentId: target.agentId,
+      },
+    });
+    if (!decision.allowed)
+      throw forbidden(
+        decision.explanation,
+        authorizationDeniedDetails(decision),
+      );
+    return bound;
+  }
+  async function head(tx: Tx, target: InstructionTarget, entryFile: string) {
+    const [result] = await tx
+      .select({ revision: revisions })
+      .from(heads)
+      .innerJoin(revisions, eq(revisions.id, heads.revisionId))
+      .where(headOwner(target, entryFile));
+    return result?.revision ?? null;
+  }
+  async function append(
+    tx: Tx,
+    target: InstructionTarget,
+    entryFile: string,
+    bytes: Buffer,
+    actor: AuthorizationActor,
+    source: AgentInstructionSource,
+    parentRevisionId: string | null,
+    baseRevisionId: string | null,
+    restoredFromRevisionId: string | null = null,
+  ) {
+    const [row] = await tx
+      .insert(revisions)
+      .values({
+        ...target,
+        entryFile,
+        contentBase64: bytes.toString("base64"),
+        contentHash: createHash("sha256").update(bytes).digest("hex"),
+        byteLength: bytes.length,
+        parentRevisionId,
+        baseRevisionId,
+        restoredFromRevisionId,
+        source,
+        actorAgentId: actor.type === "agent" ? actor.agentId : null,
+        actorUserId: actor.type === "board" ? actor.userId : null,
+        responsibleUserId:
+          actor.type === "board" ? actor.userId : actor.onBehalfOfUserId,
+        sourceRunId: actor.runId,
+      })
+      .returning();
+    await tx
+      .insert(heads)
+      .values({ ...target, entryFile, revisionId: row.id })
+      .onConflictDoUpdate({
+        target: [heads.companyId, heads.agentId, heads.entryFile],
+        set: { revisionId: row.id, updatedAt: new Date() },
+      });
+    await tx.insert(activityLog).values({
+      companyId: target.companyId,
+      actorType: actor.type === "board" ? "user" : "agent",
+      actorId: (actor.type === "board" ? actor.userId : actor.agentId)!,
+      agentId: actor.type === "agent" ? actor.agentId : null,
+      runId: actor.runId,
+      responsibleUserId: row.responsibleUserId,
+      action: "agent.instructions_revision_committed",
+      entityType: "agent",
+      entityId: target.agentId,
+      details: {
+        revisionId: row.id,
+        entryFile,
+        source,
+        parentRevisionId,
+        baseRevisionId,
+        contentHash: row.contentHash,
+        byteLength: row.byteLength,
+      },
+    });
+    return row;
+  }
+  async function seed(
+    tx: Tx,
+    target: InstructionTarget,
+    state: Awaited<ReturnType<typeof lockTarget>>,
+    actor: AuthorizationActor,
+  ) {
+    const current = await head(tx, target, state.entryFile);
+    if (current) return current;
+    const bytes = await readInstructionBytes(state.root, state.entryFile);
+    // Never scan for a fallback entry. An unconfigured legacy inline prompt is
+    // migrated only on an explicit content commit; reads preserve configured bytes.
+    if (!bytes) return null;
+    return append(
+      tx,
+      target,
+      state.entryFile,
+      bytes,
+      actor,
+      "seed",
+      null,
+      null,
+    );
+  }
+  async function getRevision(
+    tx: Tx,
+    target: InstructionTarget,
+    entryFile: string,
+    id: string,
+  ) {
+    const [row] = await tx
+      .select()
+      .from(revisions)
+      .where(and(owner(target, entryFile), eq(revisions.id, id)));
+    if (!row) throw notFound("Instruction revision not found");
+    return row;
+  }
+  async function readCurrent(
+    target: InstructionTarget,
+    actor: AuthorizationActor,
+  ): Promise<AgentInstructionSnapshot | null> {
+    return db.transaction(async (tx) => {
+      const state = await lockTarget(tx, target, actor);
+      const bound = await authorizeRead(tx, actor, target);
+      const row = await seed(tx, target, state, bound);
+      return row ? snapshot(row) : null;
+    });
+  }
+  /** Rebuild disk from the current committed head under the same lock as commits. Safe after restart. */
+  async function materializeCurrent(target: InstructionTarget): Promise<void> {
+    await db.transaction(async (tx) => {
+      const state = await lockTarget(tx, target);
+      const current = await head(tx, target, state.entryFile);
+      if (!current) throw notFound("Instruction head not found");
+      await materializeInstructionBytes(
+        state.root,
+        state.entryFile,
+        Buffer.from(current.contentBase64, "base64"),
+      );
+    });
+  }
+  async function commitInternal(
+    input:
+      | InstructionCommitInput
+      | (Omit<InstructionCommitInput, "content" | "source"> & {
+          restoreRevisionId: string;
+        }),
+    actor: AuthorizationActor,
+  ): Promise<AgentInstructionCommitReceipt> {
+    instructionPath(input.entryFile);
+    const bytes = "content" in input ? instructionBytes(input.content) : null;
+    const result = await db.transaction(async (tx) => {
+      const state = await lockTarget(tx, input, actor);
+      const bound = await authorizeInstructionCommit(tx, actor, state.agent);
+      if (state.entryFile !== input.entryFile)
+        throw conflict(
+          "Configured instruction entry changed; read the current entry and retry",
+          { code: "INSTRUCTION_ENTRY_CHANGED", entryFile: state.entryFile },
+        );
+      await assertInstructionPathSafe(state.root, state.entryFile);
+      const persistedHead = await head(tx, input, state.entryFile);
+      const current = persistedHead ?? (await seed(tx, input, state, bound));
+      const restored =
+        "restoreRevisionId" in input
+          ? await getRevision(
+              tx,
+              input,
+              input.entryFile,
+              input.restoreRevisionId,
+            )
+          : null;
+      const candidate = bytes ?? Buffer.from(restored!.contentBase64, "base64");
+      // An exact replay can safely return the durable receipt even after its base
+      // advanced. Restore also deduplicates identical content, preserving history.
+      if (current && current.contentBase64 === candidate.toString("base64"))
+        return { row: current, changed: false };
+      if ((current?.id ?? null) !== input.baseRevisionId) {
+        throw conflict(
+          "Instructions changed since the base revision. Read the current entry before saving.",
+          {
+            code: "INSTRUCTION_REVISION_CONFLICT",
+            baseRevisionId: input.baseRevisionId,
+            // A seed created in this transaction rolls back with the conflict.
+            currentRevisionId: persistedHead?.id ?? null,
+          },
+        );
+      }
+      const row = await append(
+        tx,
+        input,
+        input.entryFile,
+        candidate,
+        bound,
+        restored ? "restore" : (input as InstructionCommitInput).source,
+        current?.id ?? null,
+        input.baseRevisionId,
+        restored?.id ?? null,
+      );
+      if (
+        !state.agent.adapterConfig.instructionsRootPath ||
+        !state.agent.adapterConfig.instructionsBundleMode
+      ) {
+        await tx
+          .update(agents)
+          .set({
+            adapterConfig: {
+              ...state.agent.adapterConfig,
+              instructionsBundleMode: "managed",
+              instructionsRootPath: state.root,
+              instructionsEntryFile: state.entryFile,
+              instructionsFilePath: `${state.root}/${state.entryFile}`,
+            },
+            updatedAt: new Date(),
+          })
+          .where(eq(agents.id, state.agent.id));
+      }
+      return { row, changed: true };
+    });
+    let materialization: AgentInstructionCommitReceipt["materialization"] =
+      "current";
+    try {
+      await materializeCurrent(input);
+    } catch {
+      materialization = "pending";
+    }
+    return {
+      ...snapshot(result.row),
+      changed: result.changed,
+      materialization,
+    };
+  }
+  async function history(
+    target: InstructionTarget & {
+      entryFile: string;
+      cursor?: string;
+      limit?: number;
+    },
+    actor: AuthorizationActor,
+  ): Promise<AgentInstructionHistory> {
+    const limit = Math.max(1, Math.min(100, target.limit ?? 50));
+    return db.transaction(async (tx) => {
+      const state = await lockTarget(tx, target, actor);
+      const bound = await authorizeRead(tx, actor, target);
+      await seed(tx, target, state, bound);
+      instructionPath(target.entryFile);
+      const cursor = target.cursor
+        ? await getRevision(tx, target, target.entryFile, target.cursor)
+        : null;
+      // Keep PostgreSQL timestamp precision; JS Date truncates microseconds and
+      // would skip revisions in the cursor's fractional millisecond.
+      const cursorTime = cursor
+        ? sql`(select created_at from agent_instruction_revisions where id = ${cursor.id})`
+        : null;
+      const rows = await tx
+        .select(revisionMetadataColumns)
+        .from(revisions)
+        .where(
+          and(
+            owner(target, target.entryFile),
+            cursor && cursorTime
+              ? or(
+                  lt(revisions.createdAt, cursorTime),
+                  and(
+                    eq(revisions.createdAt, cursorTime),
+                    lt(revisions.id, cursor.id),
+                  ),
+                )
+              : undefined,
+          ),
+        )
+        .orderBy(desc(revisions.createdAt), desc(revisions.id))
+        .limit(limit + 1);
+      return {
+        revisions: rows.slice(0, limit).map(metadata),
+        nextCursor: rows.length > limit ? rows[limit - 1]!.id : null,
+      };
+    });
+  }
+  async function readRevision(
+    target: InstructionTarget & { entryFile: string; revisionId: string },
+    actor: AuthorizationActor,
+  ) {
+    return db.transaction(async (tx) => {
+      await lockTarget(tx, target, actor);
+      await authorizeRead(tx, actor, target);
+      return snapshot(
+        await getRevision(
+          tx,
+          target,
+          instructionPath(target.entryFile),
+          target.revisionId,
+        ),
+      );
+    });
+  }
+  async function diff(
+    target: InstructionTarget & {
+      entryFile: string;
+      fromRevisionId: string;
+      toRevisionId: string;
+    },
+    actor: AuthorizationActor,
+  ): Promise<AgentInstructionDiff> {
+    const from = await readRevision(
+      { ...target, revisionId: target.fromRevisionId },
+      actor,
+    );
+    const to = await readRevision(
+      { ...target, revisionId: target.toRevisionId },
+      actor,
+    );
+    // Linear, bounded exact replacement diff. Code points keep surrogate pairs intact.
+    const a = Array.from(from.content),
+      b = Array.from(to.content);
+    let start = 0,
+      end = 0;
+    while (start < a.length && start < b.length && a[start] === b[start])
+      start++;
+    while (
+      end < a.length - start &&
+      end < b.length - start &&
+      a[a.length - end - 1] === b[b.length - end - 1]
+    )
+      end++;
+    return {
+      from,
+      to,
+      prefix: a.slice(0, start).join(""),
+      removed: a.slice(start, a.length - end).join(""),
+      added: b.slice(start, b.length - end).join(""),
+      suffix: end ? a.slice(-end).join("") : "",
+    };
+  }
+  return {
+    readCurrent,
+    readRevision,
+    history,
+    diff,
+    materializeCurrent,
+    commit: (input: InstructionCommitInput, actor: AuthorizationActor) =>
+      commitInternal(input, actor),
+    restore: (
+      input: InstructionTarget & {
+        entryFile: string;
+        baseRevisionId: string;
+        revisionId: string;
+      },
+      actor: AuthorizationActor,
+    ) =>
+      commitInternal({ ...input, restoreRevisionId: input.revisionId }, actor),
+  };
+}
diff --git a/server/src/services/agent-instructions.ts b/server/src/services/agent-instructions.ts
index 5045143eb70..43c0a6e63ec 100644
--- a/server/src/services/agent-instructions.ts
+++ b/server/src/services/agent-instructions.ts
@@ -1,5 +1,8 @@
 import fs from "node:fs/promises";
 import path from "node:path";
+import { and, eq } from "drizzle-orm";
+import { agentInstructionHeads, agents, type Db } from "@paperclipai/db";
+import { instructionPath, assertInstructionPathSafe, instructionBytes, readInstructionBytes } from "./agent-instruction-files.js";
 import { notFound, unprocessable } from "../errors.js";
 import { resolveHomeAwarePath, resolvePaperclipInstanceRoot } from "../home-paths.js";
 
@@ -112,11 +115,7 @@ function isMarkdown(relativePath: string) {
 }
 
 function normalizeRelativeFilePath(candidatePath: string): string {
-  const normalized = path.posix.normalize(candidatePath.replaceAll("\\", "/")).replace(/^\/+/, "");
-  if (!normalized || normalized === "." || normalized === ".." || normalized.startsWith("../")) {
-    throw unprocessable("Instructions file path must stay within the bundle root");
-  }
-  return normalized;
+  return instructionPath(candidatePath);
 }
 
 function resolvePathWithinRoot(rootPath: string, relativePath: string): string {
@@ -130,7 +129,7 @@ function resolvePathWithinRoot(rootPath: string, relativePath: string): string {
   return absolutePath;
 }
 
-function resolveManagedInstructionsRoot(agent: AgentLike): string {
+export function resolveManagedInstructionsRoot(agent: AgentLike): string {
   return path.resolve(
     resolvePaperclipInstanceRoot(),
     "companies",
@@ -153,7 +152,7 @@ function resolveLegacyInstructionsPath(candidatePath: string, config: Record<str
 }
 
 async function statIfExists(targetPath: string) {
-  return fs.stat(targetPath).catch(() => null);
+  return fs.lstat(targetPath).catch(() => null);
 }
 
 function shouldIgnoreInstructionsEntry(entry: { name: string; isDirectory(): boolean; isFile(): boolean }) {
@@ -231,7 +230,7 @@ async function readLegacyInstructions(agent: AgentLike, config: Record<string, u
   return asString(config[PROMPT_KEY]) ?? "";
 }
 
-function deriveBundleState(agent: AgentLike): BundleState {
+export function deriveBundleState(agent: AgentLike): BundleState {
   const config = asRecord(agent.adapterConfig);
   const warnings: string[] = [];
   const storedModeRaw = config[MODE_KEY];
@@ -244,22 +243,18 @@ function deriveBundleState(agent: AgentLike): BundleState {
 
   const storedEntryRaw = asString(config[ENTRY_KEY]);
   if (storedEntryRaw) {
-    try {
-      entryFile = normalizeRelativeFilePath(storedEntryRaw);
-    } catch {
-      warnings.push(`Ignored invalid instructions entry file "${storedEntryRaw}".`);
-    }
+    entryFile = normalizeRelativeFilePath(storedEntryRaw);
   }
 
   if (!rootPath && legacyInstructionsPath) {
     try {
       const resolvedLegacyPath = resolveLegacyInstructionsPath(legacyInstructionsPath, config);
-      rootPath = path.dirname(resolvedLegacyPath);
-      entryFile = path.basename(resolvedLegacyPath);
-      mode = resolvedLegacyPath.startsWith(`${resolveManagedInstructionsRoot(agent)}${path.sep}`)
-        || resolvedLegacyPath === path.join(resolveManagedInstructionsRoot(agent), entryFile)
-        ? "managed"
-        : "external";
+      const managedRoot = resolveManagedInstructionsRoot(agent);
+      const managedRelative = path.relative(managedRoot, resolvedLegacyPath);
+      const inManagedRoot = managedRelative !== ".." && !managedRelative.startsWith(`..${path.sep}`) && !path.isAbsolute(managedRelative);
+      rootPath = inManagedRoot ? managedRoot : path.dirname(resolvedLegacyPath);
+      entryFile = inManagedRoot ? instructionPath(managedRelative.split(path.sep).join("/")) : path.basename(resolvedLegacyPath);
+      mode = inManagedRoot ? "managed" : "external";
       if (!path.isAbsolute(legacyInstructionsPath)) {
         warnings.push("Using legacy relative instructionsFilePath; migrate this agent to a managed or absolute external bundle.");
       }
@@ -303,7 +298,7 @@ async function recoverManagedBundleState(agent: AgentLike, state: BundleState):
   const files = await listFilesRecursive(managedRootPath);
   if (files.length === 0) return state;
 
-  const recoveredEntryFile = files.includes(state.entryFile)
+  const recoveredEntryFile = asString(state.config[ENTRY_KEY]) ? state.entryFile : files.includes(state.entryFile)
     ? state.entryFile
     : files.includes(ENTRY_FILE_DEFAULT)
       ? ENTRY_FILE_DEFAULT
@@ -443,7 +438,8 @@ async function writeBundleFiles(
 ) {
   for (const [relativePath, content] of Object.entries(files)) {
     const normalizedPath = normalizeRelativeFilePath(relativePath);
-    const absolutePath = resolvePathWithinRoot(rootPath, normalizedPath);
+    instructionBytes(content);
+    const absolutePath = await assertInstructionPathSafe(rootPath, normalizedPath);
     const existingStat = await statIfExists(absolutePath);
     if (existingStat?.isFile() && !options?.overwriteExisting) continue;
     await fs.mkdir(path.dirname(absolutePath), { recursive: true });
@@ -464,19 +460,26 @@ export function syncInstructionsBundleConfigFromFilePath(
     return next;
   }
   const resolvedPath = resolveLegacyInstructionsPath(instructionsFilePath, adapterConfig);
-  const rootPath = path.dirname(resolvedPath);
-  const entryFile = path.basename(resolvedPath);
-  const mode: BundleMode = resolvedPath.startsWith(`${resolveManagedInstructionsRoot(agent)}${path.sep}`)
-    || resolvedPath === path.join(resolveManagedInstructionsRoot(agent), entryFile)
-    ? "managed"
-    : "external";
+  const managedRoot = resolveManagedInstructionsRoot(agent);
+  const relative = path.relative(managedRoot, resolvedPath);
+  const managed = relative !== ".." && !relative.startsWith(`..${path.sep}`) && !path.isAbsolute(relative);
+  const rootPath = managed ? managedRoot : path.dirname(resolvedPath);
+  const entryFile = managed ? instructionPath(relative.split(path.sep).join("/")) : path.basename(resolvedPath);
+  const mode: BundleMode = managed ? "managed" : "external";
   return applyBundleConfig(next, { mode, rootPath, entryFile });
 }
 
-export function agentInstructionsService() {
+export function agentInstructionsService(db?: Db) {
+  async function assertUnversionedEntry(agent: AgentLike, entryFile: string, connection: Db | Parameters<Parameters<Db["transaction"]>[0]>[0] | undefined = db) {
+    if (!connection) throw unprocessable("Bundle initialization requires the database-backed instructions service");
+    const [head] = await connection.select().from(agentInstructionHeads).where(and(eq(agentInstructionHeads.companyId, agent.companyId),
+      eq(agentInstructionHeads.agentId, agent.id), eq(agentInstructionHeads.entryFile, entryFile)));
+    if (head) throw unprocessable("This entry has revision history. Use the instruction content API with its baseRevisionId to update it.", { code: "INSTRUCTION_REVISION_REQUIRED" });
+  }
   async function getBundle(agent: AgentLike): Promise<AgentInstructionsBundle> {
     const state = await recoverManagedBundleState(agent, deriveBundleState(agent));
     if (!state.rootPath) return toBundle(agent, state, []);
+    await assertInstructionPathSafe(state.rootPath, state.entryFile);
     const stat = await statIfExists(state.rootPath);
     if (!stat?.isDirectory()) {
       return toBundle(agent, {
@@ -507,6 +510,7 @@ export function agentInstructionsService() {
       };
     }
     if (!state.rootPath) throw notFound("Agent instructions bundle is not configured");
+    await assertInstructionPathSafe(state.rootPath, relativePath);
     const absolutePath = resolvePathWithinRoot(state.rootPath, relativePath);
     const [content, stat] = await Promise.all([
       fs.readFile(absolutePath, "utf8").catch(() => null),
@@ -551,11 +555,12 @@ export function agentInstructionsService() {
     });
     await fs.mkdir(managedRoot, { recursive: true });
 
-    const entryPath = resolvePathWithinRoot(managedRoot, entryFile);
+    const entryPath = await assertInstructionPathSafe(managedRoot, entryFile);
     const entryStat = await statIfExists(entryPath);
     if (!entryStat?.isFile()) {
       const legacyInstructions = await readLegacyInstructions(agent, current.config);
       if (legacyInstructions.trim().length > 0) {
+        await assertUnversionedEntry(agent, entryFile);
         await fs.mkdir(path.dirname(entryPath), { recursive: true });
         await fs.writeFile(entryPath, legacyInstructions, "utf8");
       }
@@ -595,9 +600,13 @@ export function agentInstructionsService() {
       nextRootPath = resolvedRoot;
     }
 
+    await assertInstructionPathSafe(nextRootPath, nextEntryFile);
     await fs.mkdir(nextRootPath, { recursive: true });
 
     const existingFiles = await listFilesRecursive(nextRootPath);
+    if (nextMode === "managed" && !existingFiles.includes(nextEntryFile)) {
+      await assertUnversionedEntry(agent, nextEntryFile);
+    }
     const exported = await exportFiles(agent);
     if (existingFiles.length === 0) {
       await writeBundleFiles(nextRootPath, exported.files);
@@ -618,7 +627,7 @@ export function agentInstructionsService() {
     return { bundle: nextBundle, adapterConfig: nextConfig };
   }
 
-  async function writeFile(
+  async function writeFileUnversioned(
     agent: AgentLike,
     relativePath: string,
     content: string,
@@ -642,7 +651,13 @@ export function agentInstructionsService() {
       return { bundle, file, adapterConfig };
     }
 
+    const configured = await recoverManagedBundleState(agent, current);
+    if (normalizeRelativeFilePath(relativePath) === configured.entryFile) {
+      throw unprocessable("Entry edits require the canonical instruction commit service and baseRevisionId", { code: "INSTRUCTION_REVISION_REQUIRED" });
+    }
     const prepared = await ensureWritableBundle(agent, options);
+    instructionBytes(content);
+    await assertInstructionPathSafe(prepared.state.rootPath!, relativePath);
     const absolutePath = resolvePathWithinRoot(prepared.state.rootPath!, relativePath);
     await fs.mkdir(path.dirname(absolutePath), { recursive: true });
     await fs.writeFile(absolutePath, content, "utf8");
@@ -654,7 +669,7 @@ export function agentInstructionsService() {
     return { bundle, file, adapterConfig: prepared.adapterConfig };
   }
 
-  async function deleteFile(agent: AgentLike, relativePath: string): Promise<{
+  async function deleteFileUnversioned(agent: AgentLike, relativePath: string): Promise<{
     bundle: AgentInstructionsBundle;
     adapterConfig: Record<string, unknown>;
   }> {
@@ -668,13 +683,35 @@ export function agentInstructionsService() {
     if (normalizedPath === state.entryFile) {
       throw unprocessable("Cannot delete the bundle entry file");
     }
-    const absolutePath = resolvePathWithinRoot(state.rootPath, normalizedPath);
+    const absolutePath = await assertInstructionPathSafe(state.rootPath, normalizedPath);
     await fs.rm(absolutePath, { force: true });
     const adapterConfig = buildPersistedBundleConfig(derived, state);
     const bundle = await getBundle({ ...agent, adapterConfig });
     return { bundle, adapterConfig };
   }
 
+  // Reload configuration under the commit lock: a previously supporting file
+  // may have become the configured entry since the route loaded its agent.
+  async function withCurrentAgent<T>(agent: AgentLike, relativePath: string, operation: (current: AgentLike) => Promise<T>) {
+    if (!db) return operation(agent);
+    return db.transaction(async (tx) => {
+      const [current] = await tx.select().from(agents)
+        .where(and(eq(agents.id, agent.id), eq(agents.companyId, agent.companyId))).for("update");
+      if (!current) throw notFound("Agent not found");
+      if (relativePath !== LEGACY_PROMPT_TEMPLATE_PATH) {
+        // Historical entries also remain projections if the configured entry changes.
+        await assertUnversionedEntry(current, normalizeRelativeFilePath(relativePath), tx);
+      }
+      return operation(current);
+    });
+  }
+  async function writeFile(...args: Parameters<typeof writeFileUnversioned>) {
+    return withCurrentAgent(args[0], args[1], (current) => writeFileUnversioned(current, args[1], args[2], args[3]));
+  }
+  async function deleteFile(...args: Parameters<typeof deleteFileUnversioned>) {
+    return withCurrentAgent(args[0], args[1], (current) => deleteFileUnversioned(current, args[1]));
+  }
+
   async function exportFiles(agent: AgentLike, options?: { rejectSymlinks?: boolean }): Promise<{
     files: Record<string, string>;
     entryFile: string;
@@ -704,7 +741,7 @@ export function agentInstructionsService() {
     };
   }
 
-  async function materializeManagedBundle(
+  async function materializeManagedBundleUnversioned(
     agent: AgentLike,
     files: Record<string, string>,
     options?: {
@@ -716,6 +753,14 @@ export function agentInstructionsService() {
     const rootPath = resolveManagedInstructionsRoot(agent);
     const entryFile = options?.entryFile ? normalizeRelativeFilePath(options.entryFile) : ENTRY_FILE_DEFAULT;
 
+    for (const [relativePath, content] of Object.entries(files)) {
+      instructionBytes(content);
+      await assertInstructionPathSafe(rootPath, relativePath);
+    }
+    const previous = await readInstructionBytes(rootPath, entryFile);
+    if (previous && !previous.equals(instructionBytes(files[entryFile] ?? ""))) {
+      throw unprocessable("Existing entry content must be saved through the canonical revision API before replacing a bundle", { code: "INSTRUCTION_REVISION_REQUIRED" });
+    }
     if (options?.replaceExisting) {
       await fs.rm(rootPath, { recursive: true, force: true });
     }
@@ -744,6 +789,24 @@ export function agentInstructionsService() {
     return { bundle, adapterConfig };
   }
 
+  async function materializeManagedBundle(
+    ...args: Parameters<typeof materializeManagedBundleUnversioned>
+  ) {
+    if (!db) throw unprocessable("Bundle initialization requires the database-backed instructions service");
+    return db.transaction(async (tx) => {
+      const agent = args[0];
+      const [owner] = await tx.select({ id: agents.id }).from(agents).where(and(eq(agents.id, agent.id), eq(agents.companyId, agent.companyId))).for("update");
+      if (!owner) throw notFound("Agent not found");
+      await assertUnversionedEntry(agent, args[2]?.entryFile ? normalizeRelativeFilePath(args[2].entryFile) : ENTRY_FILE_DEFAULT, tx);
+      if (args[2]?.replaceExisting) {
+        const [existingHead] = await tx.select({ id: agentInstructionHeads.revisionId }).from(agentInstructionHeads)
+          .where(and(eq(agentInstructionHeads.companyId, agent.companyId), eq(agentInstructionHeads.agentId, agent.id))).limit(1);
+        if (existingHead) throw unprocessable("Replacing this bundle would remove a versioned entry. Use canonical content commits.", { code: "INSTRUCTION_REVISION_REQUIRED" });
+      }
+      return materializeManagedBundleUnversioned(...args);
+    });
+  }
+
   return {
     getBundle,
     readFile,
diff --git a/server/src/services/authorization.ts b/server/src/services/authorization.ts
index 70b1d2032cf..9c4305e2410 100644
--- a/server/src/services/authorization.ts
+++ b/server/src/services/authorization.ts
@@ -62,6 +62,7 @@ export type AuthorizationAction =
   | PermissionKey
   | "agent_config:read"
   | "agent_config:update"
+  | "agent_instructions:update"
   | "skill_config:update"
   | "agent:read"
   | "agent:wake"
@@ -148,7 +149,7 @@ function companyIdForResource(resource: AuthorizationResource) {
 }
 
 function permissionForAction(action: AuthorizationAction): PermissionKey | null {
-  if (action === "agent_config:read" || action === "agent_config:update" || action === "skill_config:update") {
+  if (action === "agent_config:read" || action === "agent_config:update" || action === "agent_instructions:update" || action === "skill_config:update") {
     return null;
   }
   if (
@@ -998,6 +999,7 @@ export function authorizationService(db: Db | DbTransaction) {
       input.action === "decision_triage:manage" ||
       input.action === "agent_config:read" ||
       input.action === "agent_config:update" ||
+      input.action === "agent_instructions:update" ||
       input.action === "skill_config:update" ||
       input.action === "inbox:manage" ||
       input.action === "runtime:manage" ||
@@ -1734,7 +1736,7 @@ export function authorizationService(db: Db | DbTransaction) {
       if (input.action === "agent_config:read") {
         return decideWithAgentConfigReadGrant("user", input.actor.userId);
       }
-      if (input.action === "agent_config:update") {
+      if (input.action === "agent_config:update" || input.action === "agent_instructions:update") {
         return decideWithProtectedChangeGrants("user", input.actor.userId, {
           direct: "agents:configure",
           suggest: "agents:suggest-changes",
@@ -2227,6 +2229,19 @@ export function authorizationService(db: Db | DbTransaction) {
       return decideWithAgentConfigReadGrant("agent", actorAgentId);
     }
 
+    if (input.action === "agent_instructions:update") {
+      if (!isSimpleAssignableAgentStatus(actorAgent.status) || !input.actor.onBehalfOfUserId) {
+        return deny({ action: input.action, reason: "deny_missing_membership", explanation: "Instruction edits require an active agent and a responsible user." });
+      }
+      // Explicit configure/suggest restrictions still govern content changes. An
+      // ordinary standard agent with no such grants inherits its user's edit access.
+      const restricted = await decideWithProtectedChangeGrants("agent", actorAgentId, {
+        direct: "agents:configure", suggest: "agents:suggest-changes",
+      });
+      if (restricted.reason !== "deny_no_grant") return restricted;
+      return allow({ action: input.action, reason: "allow_company_agent", explanation: "Standard agent content edit, subject to the responsible user's target edit access." });
+    }
+
     if (input.action === "agent_config:update") {
       return decideWithProtectedChangeGrants("agent", actorAgentId, {
         direct: "agents:configure",
@@ -2391,7 +2406,7 @@ export function authorizationService(db: Db | DbTransaction) {
       responsibleUserId,
     }, "responsible-user authorization intersection denied");
 
-    return responsibleUserAuthzShadowMode() ? agentDecision : denied;
+    return input.action !== "agent_instructions:update" && responsibleUserAuthzShadowMode() ? agentDecision : denied;
   }
 
   async function decide(input: {
diff --git a/server/src/services/built-in-agents.ts b/server/src/services/built-in-agents.ts
index 718263668eb..86e035e627d 100644
--- a/server/src/services/built-in-agents.ts
+++ b/server/src/services/built-in-agents.ts
@@ -10,7 +10,9 @@ import { syncRoutineVariablesWithTemplate } from "@paperclipai/shared";
 import type { Agent, Approval, CompanySkill, PermissionKey, Routine, RoutineTrigger, RoutineVariable } from "@paperclipai/shared";
 import { conflict, HttpError, notFound, unprocessable } from "../errors.js";
 import { logActivity } from "./activity-log.js";
-import { agentInstructionsService } from "./agent-instructions.js";
+import { agentInstructionRevisionService } from "./agent-instruction-revisions.js";
+import type { AuthorizationActor } from "./authorization.js";
+import { agentInstructionsBundleMode, agentInstructionsService } from "./agent-instructions.js";
 import { agentService } from "./agents.js";
 import { approvalService } from "./approvals.js";
 import {
@@ -802,7 +804,7 @@ export function builtInAgentService(db: Db) {
   const agentSvc = agentService(db);
   const accessSvc = accessService(db);
   const approvalSvc = approvalService(db);
-  const instructionsSvc = agentInstructionsService();
+  const instructionsSvc = agentInstructionsService(db);
   const skillSvc = companySkillService(db);
   const routineSvc = routineService(db);
 
@@ -952,10 +954,15 @@ export function builtInAgentService(db: Db) {
     return currentFiles;
   }
 
-  async function materializeInstructions(agent: Agent, definition: BuiltInAgentDefinition, mode: "reconcile" | "reset") {
+  async function materializeInstructions(agent: Agent, definition: BuiltInAgentDefinition, mode: "reconcile" | "reset", actor?: AuthorizationActor) {
     const bundle = definition.bundle!;
     const stock = stockHash(bundle.instructions.files);
     const binding = await getManagedResourceBinding(agent.companyId, definition.key, "instructions", "AGENTS.md");
+    // Stock operations also read the committed projection after interrupted writes.
+    if (agentInstructionsBundleMode(agent) === "managed") {
+      try { await agentInstructionRevisionService(db).materializeCurrent({ companyId: agent.companyId, agentId: agent.id }); }
+      catch (error) { if (!(error instanceof HttpError && error.status === 404)) throw error; }
+    }
     const currentFiles = await currentInstructionFiles(agent, bundle);
     const currentHash = Object.values(currentFiles).some((value) => value === null) ? null : stockHash(currentFiles);
     const currentState = stockState({
@@ -992,13 +999,41 @@ export function builtInAgentService(db: Db) {
       return currentState;
     }
 
-    const materialized = await instructionsSvc.materializeManagedBundle(agent, bundle.instructions.files, {
-      entryFile: bundle.instructions.entryFile,
-      replaceExisting: true,
-      clearLegacyPromptTemplate: true,
-    });
+    let adapterConfig: Record<string, unknown>;
+    if (currentFiles[bundle.instructions.entryFile] !== null && currentFiles[bundle.instructions.entryFile] !== undefined) {
+      // Automatic stock reconciliation cannot invent responsible-user authority.
+      // The stock update remains visible until an authenticated reset applies it.
+      if (!actor && mode === "reconcile") return currentState;
+      if (!actor) throw unprocessable("Resetting existing instructions requires an authenticated operator", { code: "INSTRUCTION_IDENTITY_INVALID" });
+      const revisions = agentInstructionRevisionService(db);
+      const target = { companyId: agent.companyId, agentId: agent.id };
+      const baseline = await revisions.readCurrent(target, actor);
+      const receipt = await revisions.commit({ ...target, entryFile: bundle.instructions.entryFile,
+        baseRevisionId: baseline?.revision.id ?? null, content: bundle.instructions.files[bundle.instructions.entryFile] ?? "",
+        source: actor.type === "board" ? "board" : "api" }, actor);
+      if (receipt.materialization === "pending") throw conflict("Instruction revision saved; retry reset to repair its disk copy", { revisionId: receipt.revision.id });
+      const refreshed = await agentSvc.getById(agent.id);
+      if (!refreshed) throw notFound("Built-in agent not found");
+      for (const [file, content] of Object.entries(bundle.instructions.files)) {
+        if (file !== bundle.instructions.entryFile) await instructionsSvc.writeFile(refreshed, file, content);
+      }
+      const currentBundle = await instructionsSvc.getBundle(refreshed);
+      for (const file of currentBundle.files) {
+        if (!file.isEntryFile && !file.virtual && !(file.path in bundle.instructions.files)) await instructionsSvc.deleteFile(refreshed, file.path);
+      }
+      adapterConfig = { ...refreshed.adapterConfig };
+      delete adapterConfig.promptTemplate;
+      delete adapterConfig.bootstrapPromptTemplate;
+    } else {
+      const materialized = await instructionsSvc.materializeManagedBundle(agent, bundle.instructions.files, {
+        entryFile: bundle.instructions.entryFile,
+        replaceExisting: true,
+        clearLegacyPromptTemplate: true,
+      });
+      adapterConfig = materialized.adapterConfig;
+    }
     const updated = await agentSvc.update(agent.id, {
-      adapterConfig: materialized.adapterConfig,
+      adapterConfig,
     }, {
       allowBuiltInAgentMetadata: true,
       recordRevision: { source: `built-in-bundle:${mode}:instructions` },
@@ -1480,13 +1515,14 @@ export function builtInAgentService(db: Db) {
     definition: BuiltInAgentDefinition,
     mode: "reconcile" | "reset",
     resources?: Array<"instructions" | "skill" | "routine">,
+    actor?: AuthorizationActor,
   ) {
     if (!definition.bundle) return [];
     const selected = new Set(resources ?? ["instructions", "skill", "routine"]);
     const existingStates = await bundleResourceStates(agent.companyId, definition, agent);
     const byKind = new Map(existingStates.map((state) => [state.resourceKind, state]));
     const instruction = selected.has("instructions")
-      ? await materializeInstructions(agent, definition, mode)
+      ? await materializeInstructions(agent, definition, mode, actor)
       : byKind.get("instructions")!;
     const refreshedAgent = await agentSvc.getById(agent.id) as Agent | null;
     if (!refreshedAgent) throw notFound("Built-in agent not found");
@@ -1847,7 +1883,7 @@ export function builtInAgentService(db: Db) {
     return state(definition, updated as Agent);
   }
 
-  async function reset(companyId: string, key: string, input: { resources?: Array<"agent" | "instructions" | "skill" | "routine"> } = {}) {
+  async function reset(companyId: string, key: string, input: { resources?: Array<"agent" | "instructions" | "skill" | "routine"> } = {}, actor?: AuthorizationActor) {
     const definition = requireBuiltInAgentDefinition(key);
     const resetAgentDefaults = !input.resources || input.resources.includes("agent");
     const current = resetAgentDefaults
@@ -1862,6 +1898,7 @@ export function builtInAgentService(db: Db) {
       definition,
       "reset",
       input.resources ? selectedBundleResources ?? [] : undefined,
+      actor,
     );
     return state(definition, await agentSvc.getById(current.agent.id) as Agent, resources);
   }
diff --git a/server/src/services/change-consent-gate.ts b/server/src/services/change-consent-gate.ts
index 8523f04bcad..4569a0f8b38 100644
--- a/server/src/services/change-consent-gate.ts
+++ b/server/src/services/change-consent-gate.ts
@@ -112,7 +112,7 @@ function expandTargetKeysForLegacyCompatibility(targetKeys: string[]) {
   return [...expanded];
 }
 
-export function changeConsentGateService(db: Db) {
+export function changeConsentGateService(db: Db | Parameters<Parameters<Db["transaction"]>[0]>[0]) {
   return {
     assertConsented: async (input: {
       companyId: string;
diff --git a/server/src/services/company-portability.ts b/server/src/services/company-portability.ts
index 7c7501f6316..701894a7610 100644
--- a/server/src/services/company-portability.ts
+++ b/server/src/services/company-portability.ts
@@ -3549,7 +3549,7 @@ export function companyPortabilityService(db: Db, storage?: StorageService) {
   const companies = companyService(db);
   const agents = agentService(db);
   const assetRecords = assetService(db);
-  const instructions = agentInstructionsService();
+  const instructions = agentInstructionsService(db);
   const access = accessService(db);
   const projects = projectService(db);
   const issues = issueService(db);
diff --git a/server/src/services/plugin-managed-agents.ts b/server/src/services/plugin-managed-agents.ts
index 13473ec8c0a..c3a1bafd437 100644
--- a/server/src/services/plugin-managed-agents.ts
+++ b/server/src/services/plugin-managed-agents.ts
@@ -180,7 +180,7 @@ export function pluginManagedAgentService(
 ) {
   const agentSvc = agentService(db);
   const approvalSvc = approvalService(db);
-  const instructions = agentInstructionsService();
+  const instructions = agentInstructionsService(db);
 
   function declarationFor(agentKey: string) {
     const declaration = options.manifest?.agents?.find((agent) => agent.agentKey === agentKey);
diff --git a/ui/src/api/agents.ts b/ui/src/api/agents.ts
index 5bde9d5e01d..b2050c0a42d 100644
--- a/ui/src/api/agents.ts
+++ b/ui/src/api/agents.ts
@@ -5,6 +5,9 @@ import type {
   AgentPermissions,
   AgentDetail,
   AgentInstructionsBundle,
+  AgentInstructionHistory,
+  AgentInstructionDiff,
+  AgentInstructionSnapshot,
   AgentInstructionsFileDetail,
   AgentSkillSnapshot,
   AdapterEnvironmentTestResult,
@@ -167,9 +170,17 @@ export const agentsApi = {
     ),
   saveInstructionsFile: (
     id: string,
-    data: { path: string; content: string; clearLegacyPromptTemplate?: boolean },
+    data: { path: string; content: string; baseRevisionId?: string | null; clearLegacyPromptTemplate?: boolean },
     companyId?: string,
   ) => api.put<AgentInstructionsFileDetail>(agentPath(id, companyId, "/instructions-bundle/file"), data),
+  instructionHistory: (id: string, path: string, companyId?: string, cursor?: string) =>
+    api.get<AgentInstructionHistory>(agentPath(id, companyId, `/instructions-bundle/history?path=${encodeURIComponent(path)}${cursor ? `&cursor=${encodeURIComponent(cursor)}` : ""}`)),
+  instructionRevision: (id: string, path: string, revisionId: string, companyId?: string) =>
+    api.get<AgentInstructionSnapshot>(agentPath(id, companyId, `/instructions-bundle/revision/${revisionId}?path=${encodeURIComponent(path)}`)),
+  instructionDiff: (id: string, path: string, from: string, to: string, companyId?: string) =>
+    api.get<AgentInstructionDiff>(agentPath(id, companyId, `/instructions-bundle/diff?path=${encodeURIComponent(path)}&from=${encodeURIComponent(from)}&to=${encodeURIComponent(to)}`)),
+  restoreInstructions: (id: string, data: { path: string; revisionId: string; baseRevisionId: string }, companyId?: string) =>
+    api.post<AgentInstructionsFileDetail>(agentPath(id, companyId, "/instructions-bundle/restore"), data),
   deleteInstructionsFile: (id: string, relativePath: string, companyId?: string) =>
     api.delete<AgentInstructionsBundle>(
       agentPath(id, companyId, `/instructions-bundle/file?path=${encodeURIComponent(relativePath)}`),
diff --git a/ui/src/components/InstructionHistory.tsx b/ui/src/components/InstructionHistory.tsx
new file mode 100644
index 00000000000..2d8dbecfdfe
--- /dev/null
+++ b/ui/src/components/InstructionHistory.tsx
@@ -0,0 +1,145 @@
+import { useState } from "react";
+import { useInfiniteQuery, useMutation, useQuery } from "@tanstack/react-query";
+import type { AgentInstructionsFileDetail } from "@paperclipai/shared";
+import { agentsApi } from "../api/agents";
+import { Button } from "./ui/button";
+
+export function InstructionHistory({
+  agentId,
+  companyId,
+  path,
+  currentRevisionId,
+  disabled,
+  onRestored,
+}: {
+  agentId: string;
+  companyId?: string;
+  path: string;
+  currentRevisionId: string;
+  disabled: boolean;
+  onRestored: (file: AgentInstructionsFileDetail) => void;
+}) {
+  const [open, setOpen] = useState(false);
+  const [selected, setSelected] = useState<string | null>(null);
+  const history = useInfiniteQuery({
+    queryKey: ["instruction-history", agentId, path, currentRevisionId],
+    queryFn: ({ pageParam }) =>
+      agentsApi.instructionHistory(agentId, path, companyId, pageParam),
+    initialPageParam: undefined as string | undefined,
+    getNextPageParam: (page) => page.nextCursor ?? undefined,
+    enabled: open,
+  });
+  const diff = useQuery({
+    queryKey: ["instruction-diff", agentId, path, selected, currentRevisionId],
+    queryFn: () =>
+      agentsApi.instructionDiff(
+        agentId,
+        path,
+        selected!,
+        currentRevisionId,
+        companyId,
+      ),
+    enabled: open && Boolean(selected),
+  });
+  const restore = useMutation({
+    mutationFn: () =>
+      agentsApi.restoreInstructions(
+        agentId,
+        { path, revisionId: selected!, baseRevisionId: currentRevisionId },
+        companyId,
+      ),
+    onSuccess: (file) => {
+      setSelected(null);
+      onRestored(file);
+    },
+  });
+  const error = history.error ?? diff.error ?? restore.error;
+  return (
+    <div className="space-y-3">
+      <Button
+        type="button"
+        size="sm"
+        variant="outline"
+        aria-expanded={open}
+        onClick={() => setOpen(!open)}
+      >
+        History
+      </Button>
+      {open && (
+        <div className="space-y-3">
+          {history.isLoading && (
+            <p className="text-sm text-muted-foreground">Loading revisions…</p>
+          )}
+          {error && (
+            <p role="alert" className="text-sm text-destructive">
+              {error.message}
+            </p>
+          )}
+          {history.data?.pages
+            .flatMap((page) => page.revisions)
+            .map((revision) => (
+              <div key={revision.id} className="flex items-center gap-3">
+                <Button
+                  type="button"
+                  size="sm"
+                  variant={selected === revision.id ? "secondary" : "ghost"}
+                  onClick={() => setSelected(revision.id)}
+                >
+                  <span className="font-mono">{revision.id.slice(0, 8)}</span>
+                </Button>
+                <span className="text-sm text-muted-foreground">
+                  {revision.source} ·{" "}
+                  {new Date(revision.createdAt).toLocaleString()}
+                  {revision.id === currentRevisionId ? " · Current" : ""}
+                </span>
+              </div>
+            ))}
+          {history.hasNextPage && (
+            <Button
+              type="button"
+              variant="ghost"
+              disabled={history.isFetchingNextPage}
+              onClick={() => void history.fetchNextPage()}
+            >
+              Older revisions
+            </Button>
+          )}
+          {diff.data && (
+            <>
+              <p className="text-sm text-muted-foreground">Selected revision</p>
+              <pre className="whitespace-pre-wrap break-words rounded-md border border-border p-3 font-mono text-sm">
+                {diff.data.from.content}
+              </pre>
+              <p className="text-sm text-muted-foreground">
+                Changes from selected revision to current
+              </p>
+              <pre className="whitespace-pre-wrap break-words rounded-md border border-border p-3 font-mono text-sm">
+                {diff.data.removed && `Removed:\n${diff.data.removed}\n`}
+                {diff.data.added && `Added:\n${diff.data.added}`}
+                {!diff.data.removed &&
+                  !diff.data.added &&
+                  "No content changes."}
+              </pre>
+              <Button
+                type="button"
+                disabled={
+                  disabled ||
+                  restore.isPending ||
+                  selected === currentRevisionId
+                }
+                onClick={() => restore.mutate()}
+              >
+                Restore as new revision
+              </Button>
+              {disabled && (
+                <p className="text-sm text-muted-foreground">
+                  Save or cancel your edits before restoring.
+                </p>
+              )}
+            </>
+          )}
+        </div>
+      )}
+    </div>
+  );
+}
diff --git a/ui/src/pages/AgentDetail.instructions.test.tsx b/ui/src/pages/AgentDetail.instructions.test.tsx
index bd33d7c435e..181da546841 100644
--- a/ui/src/pages/AgentDetail.instructions.test.tsx
+++ b/ui/src/pages/AgentDetail.instructions.test.tsx
@@ -14,6 +14,9 @@ const mockAgentsApi = vi.hoisted(() => ({
   updateInstructionsBundle: vi.fn(),
   saveInstructionsFile: vi.fn(),
   deleteInstructionsFile: vi.fn(),
+  instructionHistory: vi.fn(),
+  instructionDiff: vi.fn(),
+  restoreInstructions: vi.fn(),
 }));
 
 const markdownEditorRenderMock = vi.hoisted(() => vi.fn());
@@ -333,6 +336,7 @@ describe("PromptsTab instruction editor", () => {
         {
           path: "AGENTS",
           content: "# Updated",
+          baseRevisionId: null,
           clearLegacyPromptTemplate: false,
         },
         "company-1",
@@ -340,6 +344,37 @@ describe("PromptsTab instruction editor", () => {
     });
   });
 
+  it("retains the draft and its base when a concurrent save conflicts", async () => {
+    const summary = makeSummary("AGENTS.md", "AGENTS.md");
+    const revision = { id: "base-1", entryFile: "AGENTS.md" } as NonNullable<AgentInstructionsFileDetail["revision"]>;
+    await renderPromptsTab(makeBundle("AGENTS.md", [summary]), { "AGENTS.md": makeDetail(summary, "original", { revision }) });
+    mockAgentsApi.saveInstructionsFile.mockRejectedValue(new Error("Instructions changed since the base revision"));
+    await selectInstructionMode("Edit");
+    const editor = container.querySelector<HTMLTextAreaElement>('[data-testid="markdown-editor"]')!;
+    await act(async () => { editor.dispatchEvent(new MouseEvent("pointerdown", { bubbles: true })); setNativeValue(editor, "my unsaved edit"); });
+    await waitFor(() => expect(saveAction).toEqual(expect.any(Function)));
+    await act(async () => { saveAction?.(); });
+    await waitFor(() => expect(container.querySelector('[role="alert"]')?.textContent).toContain("base revision"));
+    expect(editor.value).toBe("my unsaved edit");
+    expect(mockAgentsApi.saveInstructionsFile).toHaveBeenCalledWith("agent-1", expect.objectContaining({ content: "my unsaved edit", baseRevisionId: "base-1" }), "company-1");
+  });
+
+  it("shows revision content and restores against the displayed current head", async () => {
+    const summary = makeSummary("AGENTS.md", "AGENTS.md");
+    const revision = { id: "current-1", entryFile: "AGENTS.md" } as NonNullable<AgentInstructionsFileDetail["revision"]>;
+    mockAgentsApi.instructionHistory.mockResolvedValue({ revisions: [{ id: "old-revision", source: "board", createdAt: "2026-01-01T00:00:00Z" }], nextCursor: null });
+    mockAgentsApi.instructionDiff.mockResolvedValue({ from: { content: "old text" }, removed: "old", added: "new" });
+    mockAgentsApi.restoreInstructions.mockResolvedValue(makeDetail(summary, "old text", { revision: { ...revision, id: "restored-1" } }));
+    await renderPromptsTab(makeBundle("AGENTS.md", [summary]), { "AGENTS.md": makeDetail(summary, "new text", { revision }) });
+    await waitFor(() => expect(buttonByText(container, "History")).toBeDefined());
+    await act(async () => { buttonByText(container, "History").click(); });
+    await waitFor(() => expect(buttonByText(container, "old-revi")).toBeDefined());
+    await act(async () => { buttonByText(container, "old-revi").click(); });
+    await waitFor(() => expect(container.textContent).toContain("old text"));
+    await act(async () => { buttonByText(container, "Restore as new revision").click(); });
+    await waitFor(() => expect(mockAgentsApi.restoreInstructions).toHaveBeenCalledWith("agent-1", { path: "AGENTS.md", revisionId: "old-revision", baseRevisionId: "current-1" }, "company-1"));
+  });
+
   it("ignores rich-editor mount normalization until the user interacts", async () => {
     const summary = makeSummary("AGENTS.md", "AGENTS.md");
     const onDirtyChange = vi.fn();
diff --git a/ui/src/pages/AgentDetail.tsx b/ui/src/pages/AgentDetail.tsx
index b6896c6f729..b18b77bde49 100644
--- a/ui/src/pages/AgentDetail.tsx
+++ b/ui/src/pages/AgentDetail.tsx
@@ -1,3 +1,4 @@
+import { InstructionHistory } from "../components/InstructionHistory";
 import { AgentCharacter } from "../components/AgentCharacter";
 import { characterStateForAgent } from "@paperclipai/shared";
 import { mergeRunLogChunks, readChunkSeq } from "../lib/run-log-chunks";
@@ -2197,6 +2198,7 @@ export function PromptsTab({
   const [instructionMode, setInstructionMode] = useState<"read" | "edit" | "raw">("read");
   const [showFilePanel, setShowFilePanel] = useState(false);
   const [draft, setDraft] = useState<string | null>(null);
+  const draftBaseRevisionRef = useRef<string | null | undefined>(undefined);
   const [bundleDraft, setBundleDraft] = useState<{
     mode: "managed" | "external";
     rootPath: string;
@@ -2225,6 +2227,7 @@ export function PromptsTab({
   }, []);
   const setSelectedFile = useCallback((filePath: string) => {
     editorInteractedRef.current = false;
+    draftBaseRevisionRef.current = undefined;
     setSelectedFileState(filePath);
   }, []);
 
@@ -2284,7 +2287,7 @@ export function PromptsTab({
   const selectedFileExists = bundleMatchesDraft && fileOptions.includes(selectedOrEntryFile);
   const selectedFileSummary = bundle?.files.find((file) => file.path === selectedOrEntryFile) ?? null;
 
-  const { data: selectedFileDetail, isLoading: fileLoading } = useQuery({
+  const { data: selectedFileDetail, isLoading: fileLoading, error: fileError } = useQuery({
     queryKey: queryKeys.agents.instructionsFile(agent.id, selectedOrEntryFile),
     queryFn: () => agentsApi.instructionsFile(agent.id, selectedOrEntryFile, companyId),
     enabled: Boolean(companyId && isLocal && selectedFileExists),
@@ -2299,9 +2302,9 @@ export function PromptsTab({
     }) => agentsApi.updateInstructionsBundle(agent.id, data, companyId),
     onMutate: () => {
       editorInteractedRef.current = false;
-      setAwaitingRefresh(true);
     },
     onSuccess: () => {
+      setAwaitingRefresh(true);
       queryClient.invalidateQueries({ queryKey: queryKeys.agents.instructionsBundle(agent.id) });
       queryClient.invalidateQueries({ queryKey: queryKeys.agents.detail(agent.id) });
       queryClient.invalidateQueries({ queryKey: queryKeys.agents.detail(agent.urlKey) });
@@ -2310,13 +2313,15 @@ export function PromptsTab({
   });
 
   const saveFile = useMutation({
-    mutationFn: (data: { path: string; content: string; clearLegacyPromptTemplate?: boolean }) =>
+    mutationFn: (data: { path: string; content: string; baseRevisionId?: string | null; clearLegacyPromptTemplate?: boolean }) =>
       agentsApi.saveInstructionsFile(agent.id, data, companyId),
     onMutate: () => {
       editorInteractedRef.current = false;
-      setAwaitingRefresh(true);
     },
-    onSuccess: (_, variables) => {
+    onSuccess: (file, variables) => {
+      setDraft(null);
+      draftBaseRevisionRef.current = undefined;
+      queryClient.setQueryData(queryKeys.agents.instructionsFile(agent.id, variables.path), file);
       setPendingFiles((prev) => prev.filter((f) => f !== variables.path));
       queryClient.invalidateQueries({ queryKey: queryKeys.agents.instructionsBundle(agent.id) });
       queryClient.invalidateQueries({ queryKey: queryKeys.agents.instructionsFile(agent.id, variables.path) });
@@ -2409,7 +2414,7 @@ export function PromptsTab({
       return;
     }
     if (lastFileVersionRef.current !== versionKey) {
-      setDraft(null);
+      if (draftBaseRevisionRef.current === undefined) setDraft(null);
       lastFileVersionRef.current = versionKey;
     }
   }, [awaitingRefresh, currentMode, currentRootPath, selectedFileDetail, selectedFileExists, selectedOrEntryFile]);
@@ -2481,6 +2486,7 @@ export function PromptsTab({
           await saveFile.mutateAsync({
             path: selectedOrEntryFile,
             content: displayValue,
+            ...(selectedOrEntryFile === currentEntryFile && currentMode === "managed" ? { baseRevisionId: draftBaseRevisionRef.current !== undefined ? draftBaseRevisionRef.current : selectedFileDetail?.revision?.id ?? null } : {}),
             clearLegacyPromptTemplate: shouldClearLegacy,
           });
         }
@@ -2495,6 +2501,9 @@ export function PromptsTab({
     fileDirty,
     isDirty,
     onSaveActionChange,
+    selectedFileDetail?.revision?.id,
+    currentEntryFile,
+    currentMode,
     saveFile,
     selectedOrEntryFile,
     updateBundle,
@@ -2502,6 +2511,7 @@ export function PromptsTab({
 
   useEffect(() => {
     onCancelActionChange(isDirty ? () => {
+      draftBaseRevisionRef.current = undefined;
       setDraft(null);
       if (bundle) {
         setBundleDraft({
@@ -2938,6 +2948,18 @@ export function PromptsTab({
             </div>
           </div>
 
+          {(saveFile.error || fileError || updateBundle.error) && <p role="alert" className="text-sm text-destructive">{(saveFile.error ?? fileError ?? updateBundle.error)?.message} Your unsaved edits are retained.</p>}
+          {selectedFileDetail?.receipt?.materialization === "pending" && <p role="status" className="text-sm text-muted-foreground">Revision saved. The instruction file still needs to be rebuilt from the saved revision.</p>}
+          {selectedFileDetail?.revision && currentMode === "managed" && <InstructionHistory
+            key={selectedOrEntryFile} agentId={agent.id} companyId={companyId} path={selectedOrEntryFile}
+            currentRevisionId={selectedFileDetail.revision.id} disabled={isDirty || isSaving}
+            onRestored={(file) => {
+              setDraft(null);
+              draftBaseRevisionRef.current = undefined;
+              queryClient.setQueryData(queryKeys.agents.instructionsFile(agent.id, selectedOrEntryFile), file);
+              queryClient.invalidateQueries({ queryKey: queryKeys.agents.instructionsBundle(agent.id) });
+            }}
+          />}
           {selectedFileExists && fileLoading && !selectedFileDetail ? (
             <PromptEditorSkeleton />
           ) : instructionMode === "read" ? (
@@ -2975,6 +2997,7 @@ export function PromptsTab({
                 value={displayValue}
                 onChange={(value) => {
                   if (!editorInteractedRef.current) return;
+                  if (draftBaseRevisionRef.current === undefined) draftBaseRevisionRef.current = selectedFileDetail?.revision?.id ?? null;
                   setDraft(value ?? "");
                 }}
                 placeholder="# Agent instructions"
@@ -2991,7 +3014,10 @@ export function PromptsTab({
             <textarea
               aria-label="Instruction file editor"
               value={displayValue}
-              onChange={(event) => setDraft(event.target.value)}
+              onChange={(event) => {
+                if (draftBaseRevisionRef.current === undefined) draftBaseRevisionRef.current = selectedFileDetail?.revision?.id ?? null;
+                setDraft(event.target.value);
+              }}
               className="min-h-(--sz-420px) w-full min-w-0 rounded-md border border-border bg-transparent px-3 py-2 font-mono text-sm outline-none"
               placeholder="File contents"
             />