fix: preserve agent instructions on adapter switch

Co-Authored-By: Paperclip <noreply@paperclip.ing>

server/src/__tests__/agent-instructions-routes.test.ts

@@ -197,4 +197,43 @@ describe("agent instructions bundle routes", () => {
       expect.any(Object),
     );
   });
+
+  it("preserves managed instructions config when switching adapters", async () => {
+    mockAgentService.getById.mockResolvedValue({
+      ...makeAgent(),
+      adapterType: "codex_local",
+      adapterConfig: {
+        instructionsBundleMode: "managed",
+        instructionsRootPath: "/tmp/agent-1",
+        instructionsEntryFile: "AGENTS.md",
+        instructionsFilePath: "/tmp/agent-1/AGENTS.md",
+        model: "gpt-5.4",
+      },
+    });
+
+    const res = await request(createApp())
+      .patch("/api/agents/11111111-1111-4111-8111-111111111111?companyId=company-1")
+      .send({
+        adapterType: "claude_local",
+        adapterConfig: {
+          model: "claude-sonnet-4",
+        },
+      });
+
+    expect(res.status, JSON.stringify(res.body)).toBe(200);
+    expect(mockAgentService.update).toHaveBeenCalledWith(
+      "11111111-1111-4111-8111-111111111111",
+      expect.objectContaining({
+        adapterType: "claude_local",
+        adapterConfig: expect.objectContaining({
+          model: "claude-sonnet-4",
+          instructionsBundleMode: "managed",
+          instructionsRootPath: "/tmp/agent-1",
+          instructionsEntryFile: "AGENTS.md",
+          instructionsFilePath: "/tmp/agent-1/AGENTS.md",
+        }),
+      }),
+      expect.any(Object),
+    );
+  });
 });

server/src/routes/agents.ts

@@ -73,6 +73,13 @@ export function agentRoutes(db: Db) {
   };
   const DEFAULT_MANAGED_INSTRUCTIONS_ADAPTER_TYPES = new Set(Object.keys(DEFAULT_INSTRUCTIONS_PATH_KEYS));
   const KNOWN_INSTRUCTIONS_PATH_KEYS = new Set(["instructionsFilePath", "agentsMdPath"]);
+  const KNOWN_INSTRUCTIONS_BUNDLE_KEYS = [
+    "instructionsBundleMode",
+    "instructionsRootPath",
+    "instructionsEntryFile",
+    "instructionsFilePath",
+    "agentsMdPath",
+  ] as const;
 
   const router = Router();
   const svc = agentService(db);
@@ -303,6 +310,24 @@ export function agentRoutes(db: Db) {
     return trimmed.length > 0 ? trimmed : null;
   }
 
+  function preserveInstructionsBundleConfig(
+    existingAdapterConfig: Record<string, unknown>,
+    nextAdapterConfig: Record<string, unknown>,
+  ) {
+    const nextKeys = new Set(Object.keys(nextAdapterConfig));
+    if (KNOWN_INSTRUCTIONS_BUNDLE_KEYS.some((key) => nextKeys.has(key))) {
+      return nextAdapterConfig;
+    }
+
+    const merged = { ...nextAdapterConfig };
+    for (const key of KNOWN_INSTRUCTIONS_BUNDLE_KEYS) {
+      if (merged[key] === undefined && existingAdapterConfig[key] !== undefined) {
+        merged[key] = existingAdapterConfig[key];
+      }
+    }
+    return merged;
+  }
+
   function parseBooleanLike(value: unknown): boolean | null {
     if (typeof value === "boolean") return value;
     if (typeof value === "number") {
@@ -1710,9 +1735,18 @@ export function agentRoutes(db: Db) {
       Object.prototype.hasOwnProperty.call(patchData, "adapterType") ||
       Object.prototype.hasOwnProperty.call(patchData, "adapterConfig");
     if (touchesAdapterConfiguration) {
-      const rawEffectiveAdapterConfig = Object.prototype.hasOwnProperty.call(patchData, "adapterConfig")
+      const existingAdapterConfig = asRecord(existing.adapterConfig) ?? {};
+      const changingAdapterType =
+        typeof patchData.adapterType === "string" && patchData.adapterType !== existing.adapterType;
+      let rawEffectiveAdapterConfig = Object.prototype.hasOwnProperty.call(patchData, "adapterConfig")
         ? (asRecord(patchData.adapterConfig) ?? {})
-        : (asRecord(existing.adapterConfig) ?? {});
+        : existingAdapterConfig;
+      if (changingAdapterType) {
+        rawEffectiveAdapterConfig = preserveInstructionsBundleConfig(
+          existingAdapterConfig,
+          rawEffectiveAdapterConfig,
+        );
+      }
       const effectiveAdapterConfig = applyCreateDefaultsByAdapterType(
         requestedAdapterType,
         rawEffectiveAdapterConfig,