diff --git a/server/src/__tests__/agent-config-revision-diff.test.ts b/server/src/__tests__/agent-config-revision-diff.test.ts
new file mode 100644
index 00000000000..32995fbd448
--- /dev/null
+++ b/server/src/__tests__/agent-config-revision-diff.test.ts
@@ -0,0 +1,33 @@
+import { describe, expect, it } from "vitest";
+import { diffConfigSnapshot } from "../services/agents.js";
+
+describe("agent config revision diff", () => {
+  it("records editor-level paths instead of broad config objects", () => {
+    const before = {
+      name: "Coder",
+      role: "engineer",
+      title: null,
+      icon: null,
+      reportsTo: null,
+      capabilities: null,
+      adapterType: "codex_local",
+      adapterConfig: { model: "gpt-5", env: { DEBUG: "0" } },
+      runtimeConfig: { heartbeat: { intervalSec: 300 }, modelProfiles: { cheap: { enabled: false } } },
+      defaultEnvironmentId: null,
+      budgetMonthlyCents: 1000,
+      metadata: null,
+    };
+    const after = {
+      ...before,
+      adapterConfig: { model: "gpt-5.5", env: { DEBUG: "1" } },
+      runtimeConfig: { heartbeat: { intervalSec: 600 }, modelProfiles: { cheap: { enabled: true } } },
+    };
+
+    expect(diffConfigSnapshot(before, after)).toEqual([
+      "adapterConfig.env",
+      "adapterConfig.model",
+      "runtimeConfig.heartbeat.intervalSec",
+      "runtimeConfig.modelProfiles.cheap",
+    ]);
+  });
+});
diff --git a/server/src/services/agents.ts b/server/src/services/agents.ts
index 00ded758323..2b1d3e1ed65 100644
--- a/server/src/services/agents.ts
+++ b/server/src/services/agents.ts
@@ -201,11 +201,49 @@ function normalizeRuntimeConfigForNewAgent(runtimeConfig: unknown): Record<strin
   return normalizedRuntimeConfig;
 }
 
-function diffConfigSnapshot(
+function diffRecordFields(
+  before: unknown,
+  after: unknown,
+  prefix: string,
+): string[] {
+  const beforeRecord = isPlainRecord(before) ? before : {};
+  const afterRecord = isPlainRecord(after) ? after : {};
+  return [...new Set([...Object.keys(beforeRecord), ...Object.keys(afterRecord)])]
+    .sort()
+    .filter((field) => !jsonEqual(beforeRecord[field], afterRecord[field]))
+    .map((field) => `${prefix}.${field}`);
+}
+
+export function diffConfigSnapshot(
   before: AgentConfigSnapshot,
   after: AgentConfigSnapshot,
 ): string[] {
-  return CONFIG_REVISION_FIELDS.filter((field) => !jsonEqual(before[field], after[field]));
+  const changedKeys: string[] = [];
+  for (const field of CONFIG_REVISION_FIELDS) {
+    if (jsonEqual(before[field], after[field])) continue;
+    if (field === "adapterConfig") {
+      changedKeys.push(...diffRecordFields(before.adapterConfig, after.adapterConfig, field));
+      continue;
+    }
+    if (field === "runtimeConfig") {
+      const beforeRuntime = isPlainRecord(before.runtimeConfig) ? before.runtimeConfig : {};
+      const afterRuntime = isPlainRecord(after.runtimeConfig) ? after.runtimeConfig : {};
+      const runtimeFields = [...new Set([...Object.keys(beforeRuntime), ...Object.keys(afterRuntime)])].sort();
+      for (const runtimeField of runtimeFields) {
+        if (jsonEqual(beforeRuntime[runtimeField], afterRuntime[runtimeField])) continue;
+        if (runtimeField === "heartbeat") {
+          changedKeys.push(...diffRecordFields(beforeRuntime.heartbeat, afterRuntime.heartbeat, "runtimeConfig.heartbeat"));
+        } else if (runtimeField === "modelProfiles") {
+          changedKeys.push(...diffRecordFields(beforeRuntime.modelProfiles, afterRuntime.modelProfiles, "runtimeConfig.modelProfiles"));
+        } else {
+          changedKeys.push(`runtimeConfig.${runtimeField}`);
+        }
+      }
+      continue;
+    }
+    changedKeys.push(field);
+  }
+  return changedKeys;
 }
 
 function configPatchFromSnapshot(snapshot: unknown): Partial<typeof agents.$inferInsert> {
diff --git a/ui/src/components/AgentConfigHistory.tsx b/ui/src/components/AgentConfigHistory.tsx
index 43851c34472..16b74644274 100644
--- a/ui/src/components/AgentConfigHistory.tsx
+++ b/ui/src/components/AgentConfigHistory.tsx
@@ -18,10 +18,14 @@ import { formatDate } from "../lib/utils";
 import { formatAgentConfigValue } from "../lib/agent-config-changeset";
 
 function valueAt(snapshot: Record<string, unknown>, key: string): unknown {
-  return key.split(".").reduce<unknown>((current, segment) => {
-    if (!current || typeof current !== "object") return undefined;
-    return (current as Record<string, unknown>)[segment];
-  }, snapshot);
+  if (Object.prototype.hasOwnProperty.call(snapshot, key)) return snapshot[key];
+  const separator = key.indexOf(".");
+  if (separator === -1) return undefined;
+  const head = key.slice(0, separator);
+  const tail = key.slice(separator + 1);
+  const next = snapshot[head];
+  if (!next || typeof next !== "object" || Array.isArray(next)) return undefined;
+  return valueAt(next as Record<string, unknown>, tail);
 }
 
 export function revisionDiff(revision: AgentConfigRevision) {
diff --git a/ui/src/lib/agent-config-changeset.test.ts b/ui/src/lib/agent-config-changeset.test.ts
index 1b57e2c0ee6..1c5dea27603 100644
--- a/ui/src/lib/agent-config-changeset.test.ts
+++ b/ui/src/lib/agent-config-changeset.test.ts
@@ -10,7 +10,7 @@ describe("agent config changeset", () => {
     expect(changes.map((change) => [change.key, change.before, change.after, change.section])).toEqual([
       ["adapterConfig.model", "gpt-5", "gpt-5.5", "Runtime"],
       ["adapterConfig.cwd", "/old", "/new", "Danger & Legacy"],
-      ["heartbeat.intervalSec", 300, 600, "Schedule & Runs"],
+      ["runtimeConfig.heartbeat.intervalSec", 300, 600, "Schedule & Runs"],
     ]);
   });
 
diff --git a/ui/src/lib/agent-config-changeset.ts b/ui/src/lib/agent-config-changeset.ts
index 9180db1136f..e5cd3968a44 100644
--- a/ui/src/lib/agent-config-changeset.ts
+++ b/ui/src/lib/agent-config-changeset.ts
@@ -16,8 +16,8 @@ function labelForKey(key: string): string {
 }
 
 function sectionForKey(key: string): AgentConfigChange["section"] {
-  if (key === "identity.defaultEnvironmentId" || key === "adapterConfig.env") return "Environment";
-  if (key.startsWith("heartbeat.")) return "Schedule & Runs";
+  if (key === "defaultEnvironmentId" || key === "adapterConfig.env") return "Environment";
+  if (key.startsWith("runtimeConfig.heartbeat.")) return "Schedule & Runs";
   if (/cwd|dangerouslySkipPermissions|dangerouslyBypassSandbox|dangerouslyBypassApprovalsAndSandbox/.test(key)) return "Danger & Legacy";
   return "Runtime";
 }
@@ -34,7 +34,13 @@ export function buildAgentConfigChanges(agent: Agent, overlay: AgentConfigOverla
   const changes: AgentConfigChange[] = [];
   const addGroup = (group: OverlayGroup) => {
     for (const [field, after] of Object.entries(overlay[group])) {
-      const key = `${group}.${field}`;
+      const key = group === "identity"
+        ? field
+        : group === "heartbeat"
+          ? `runtimeConfig.heartbeat.${field}`
+          : group === "runtime"
+            ? field
+            : `adapterConfig.${field}`;
       changes.push({ key, label: labelForKey(key), section: sectionForKey(key), before: originalValue(agent, group, field), after });
     }
   };
@@ -45,16 +51,31 @@ export function buildAgentConfigChanges(agent: Agent, overlay: AgentConfigOverla
   addGroup("runtime");
   if (overlay.modelProfiles?.cheap !== undefined) {
     const profiles = ((agent.runtimeConfig ?? {}) as Record<string, unknown>).modelProfiles as Record<string, unknown> | undefined;
-    changes.push({ key: "modelProfiles.cheap", label: "Cost saver model", section: "Runtime", before: profiles?.cheap, after: overlay.modelProfiles.cheap });
+    changes.push({ key: "runtimeConfig.modelProfiles.cheap", label: "Cost saver model", section: "Runtime", before: profiles?.cheap, after: overlay.modelProfiles.cheap });
   }
   return changes;
 }
 
 export function revertAgentConfigChange(overlay: AgentConfigOverlay, key: string): AgentConfigOverlay {
   if (key === "adapterType") return { ...overlay, adapterType: undefined };
-  if (key === "modelProfiles.cheap") return { ...overlay, modelProfiles: undefined };
-  const [group, field] = key.split(".", 2) as [OverlayGroup, string];
-  if (!field || !(group in overlay)) return overlay;
+  if (key === "runtimeConfig.modelProfiles.cheap") return { ...overlay, modelProfiles: undefined };
+  let group: OverlayGroup;
+  let field: string;
+  if (key.startsWith("adapterConfig.")) {
+    group = "adapterConfig";
+    field = key.slice("adapterConfig.".length);
+  } else if (key.startsWith("runtimeConfig.heartbeat.")) {
+    group = "heartbeat";
+    field = key.slice("runtimeConfig.heartbeat.".length);
+  } else if (key in overlay.identity) {
+    group = "identity";
+    field = key;
+  } else if (key in overlay.runtime) {
+    group = "runtime";
+    field = key;
+  } else {
+    return overlay;
+  }
   const nextGroup = { ...overlay[group] };
   delete nextGroup[field];
   return { ...overlay, [group]: nextGroup };