diff --git a/doc/COST-ACCOUNTING.md b/doc/COST-ACCOUNTING.md
index f3c10b14bb6..4363f279cdf 100644
--- a/doc/COST-ACCOUNTING.md
+++ b/doc/COST-ACCOUNTING.md
@@ -166,7 +166,9 @@ provider adapters with missing prices still do.
 
 Budget policy updates may omit unchanged settings, including the amount for an
 existing policy. Omitted settings are read under the accounting transaction lock.
-Creating a policy still requires an amount. Generic agent and company budget
+Creating a policy still requires an amount. Partial edits preserve an explicitly
+disabled policy; the legacy monthly-cap endpoints explicitly enable a positive
+cap and disable a zero cap. Generic agent and company budget
 edits deliver hard-stop cancellation after their transaction commits.
 
 Status-card update costs retain the ledger's fractional-cent storage precision.
diff --git a/scripts/test-accounting-mutations.mjs b/scripts/test-accounting-mutations.mjs
index 5cbb19022b2..79f27f6b0be 100644
--- a/scripts/test-accounting-mutations.mjs
+++ b/scripts/test-accounting-mutations.mjs
@@ -9,6 +9,7 @@ const artifactDirectory = path.join(root, "coverage/accounting/mutations");
 const targets = { deduplication: "deduplicates a retried receipt", company: "isolates company reporting", projection: "conserves agent projections", threshold: "stops at the exact budget boundary" };
 const evidence = [];
 const persist = () => writeFile(path.join(root, "coverage/accounting/mutations.json"), JSON.stringify({ generatedAt: new Date().toISOString(), evidence }, null, 2));
+await rm(artifactDirectory, { recursive: true, force: true });
 await mkdir(artifactDirectory, { recursive: true });
 try {
   for (const name of ["baseline", ...Object.keys(targets)]) {
diff --git a/server/src/__tests__/cost-accounting-reliability.test.ts b/server/src/__tests__/cost-accounting-reliability.test.ts
index 642c25f8b12..8e285800d0f 100644
--- a/server/src/__tests__/cost-accounting-reliability.test.ts
+++ b/server/src/__tests__/cost-accounting-reliability.test.ts
@@ -311,6 +311,10 @@ databaseDescribe("cost accounting reliability (PostgreSQL)", () => {
     await budgets.upsertPolicy(f.company.id, { ...identity, amount: 200, hardStopEnabled: false, warnPercent: 60, notifyEnabled: false }, "other-operator");
     const saved = await budgets.upsertPolicy(f.company.id, upsertBudgetPolicySchema.parse({ ...identity, reservationCents: "10" }), "board");
     expect(saved).toMatchObject({ amount: 200, hardStopEnabled: false, warnPercent: 60, notifyEnabled: false, reservationCents: "10.0000000" });
+    await budgets.upsertPolicy(f.company.id, { ...identity, isActive: false }, "other-operator");
+    const disabled = await budgets.upsertPolicy(f.company.id, upsertBudgetPolicySchema.parse({ ...identity, amount: 300 }), "board");
+    expect(await db.select({ amount: budgetPolicies.amount, isActive: budgetPolicies.isActive }).from(budgetPolicies).where(eq(budgetPolicies.id, disabled.policyId))).toEqual([{ amount: 300, isActive: false }]);
+    expect(disabled).toMatchObject({ amount: 0, isActive: false, hardStopEnabled: false, warnPercent: 60, notifyEnabled: false, reservationCents: "10.0000000" });
     await expect(budgets.upsertPolicy(f.company.id, { scopeType: "project", scopeId: f.project.id, reservationCents: "1" }, "board")).rejects.toThrow("Amount is required");
   });
 
diff --git a/server/src/__tests__/costs-service.test.ts b/server/src/__tests__/costs-service.test.ts
index 4c4057aa3ac..862ac09c666 100644
--- a/server/src/__tests__/costs-service.test.ts
+++ b/server/src/__tests__/costs-service.test.ts
@@ -398,6 +398,7 @@ describe("cost routes", () => {
         scopeType: "agent",
         scopeId: "agent-1",
         amount: 2500,
+        isActive: true,
         windowKind: "calendar_month_utc",
       },
       "board-user",
diff --git a/server/src/routes/companies.ts b/server/src/routes/companies.ts
index 678d1c6c921..8de78282c20 100644
--- a/server/src/routes/companies.ts
+++ b/server/src/routes/companies.ts
@@ -279,8 +279,9 @@ export function companyRoutes(db: Db, storage?: StorageService, options?: Compan
   const router = Router();
   const importTransferSpoolRoot =
     options?.importTransferSpoolRoot ?? resolveDefaultImportTransferSpoolRoot();
-  const heartbeat = heartbeatService(db);
-  const svc = companyService(db, { cancelWorkForScope: heartbeat.cancelBudgetScopeWork });
+  const svc = companyService(db, {
+    cancelWorkForScope: (scope) => heartbeatService(db).cancelBudgetScopeWork(scope),
+  });
   const agents = agentService(db);
   const portability = companyPortabilityService(db, storage);
   const access = accessService(db);
diff --git a/server/src/routes/costs.ts b/server/src/routes/costs.ts
index d30a4de3877..b887f08be30 100644
--- a/server/src/routes/costs.ts
+++ b/server/src/routes/costs.ts
@@ -325,6 +325,7 @@ export function costRoutes(
         scopeType: "company",
         scopeId: companyId,
         amount: req.body.budgetMonthlyCents,
+        isActive: req.body.budgetMonthlyCents > 0,
         windowKind: "calendar_month_utc",
       },
       req.actor.userId ?? "board",
@@ -346,6 +347,7 @@ export function costRoutes(
         scopeType: "agent",
         scopeId: agent.id,
         amount: req.body.budgetMonthlyCents,
+        isActive: req.body.budgetMonthlyCents > 0,
         windowKind: "calendar_month_utc",
       },
       req.actor.type === "board" ? req.actor.userId ?? "board" : null,
diff --git a/server/src/services/agents.ts b/server/src/services/agents.ts
index 6829fb6e4ac..aed0355d3ba 100644
--- a/server/src/services/agents.ts
+++ b/server/src/services/agents.ts
@@ -831,7 +831,7 @@ export function agentService(db: Db, budgetHooks: BudgetServiceHooks = {}) {
 
       if (normalizedPatch.budgetMonthlyCents !== undefined) {
         await budgetServiceInTransaction(txDb, publications).upsertPolicy(existing.companyId, {
-          scopeType: "agent", scopeId: id, amount: normalizedPatch.budgetMonthlyCents, windowKind: "calendar_month_utc",
+          scopeType: "agent", scopeId: id, amount: normalizedPatch.budgetMonthlyCents, isActive: normalizedPatch.budgetMonthlyCents > 0, windowKind: "calendar_month_utc",
         }, options?.recordRevision?.createdByUserId ?? null);
       }
       const normalizedUpdated = await agentService(txDb).getById(updated.id);
diff --git a/server/src/services/budgets.ts b/server/src/services/budgets.ts
index 91ccc2e1880..83e304364aa 100644
--- a/server/src/services/budgets.ts
+++ b/server/src/services/budgets.ts
@@ -627,7 +627,7 @@ export function budgetServiceInTransaction(db: Db, publications: ActivityPublica
 
       if (!existing && input.amount === undefined) throw unprocessable("Amount is required for a new budget policy");
       const amount = Math.max(0, Math.floor(input.amount ?? existing!.amount));
-      const nextIsActive = amount > 0 && (input.isActive ?? (input.amount !== undefined ? true : existing?.isActive ?? true));
+      const nextIsActive = amount > 0 && (input.isActive ?? existing?.isActive ?? true);
       const now = new Date();
       const row = existing
         ? await db
diff --git a/server/src/services/companies.ts b/server/src/services/companies.ts
index 1abc4321b82..c83e214a9ba 100644
--- a/server/src/services/companies.ts
+++ b/server/src/services/companies.ts
@@ -439,7 +439,7 @@ export function companyService(db: Db, budgetHooks: BudgetServiceHooks = {}) {
 
         if (data.budgetMonthlyCents !== undefined) {
           await budgetServiceInTransaction(tx as unknown as Db, budgetPublications).upsertPolicy(id, {
-            scopeType: "company", scopeId: id, amount: data.budgetMonthlyCents, windowKind: "calendar_month_utc",
+            scopeType: "company", scopeId: id, amount: data.budgetMonthlyCents, isActive: data.budgetMonthlyCents > 0, windowKind: "calendar_month_utc",
           }, actor.actorType === "user" ? actor.actorId : null);
           const [budgetUpdated] = await tx.select().from(companies).where(eq(companies.id, id));
           Object.assign(updated, budgetUpdated);