C4 follow-up #3: RFC 8594 Deprecation/Sunset headers + call counter on legacy hire routes

src/main/api-server/deprecation-counter.ts

@@ -0,0 +1,36 @@
+/**
+ * In-process counter for deprecated HTTP routes (C4-followup #3).
+ *
+ * The counters let us assert "legacy HTTP hire traffic has hit zero"
+ * before physically deleting the deprecated handlers. Keys are the
+ * route label the handler passes in (e.g. `POST /api/companies/:companyId/agents`).
+ *
+ * Scope is intentionally narrow: module-level Map, synchronous mutation,
+ * no IO, no fallback. An empty label is a programmer error — we throw
+ * so it surfaces in tests instead of silently recording under "".
+ *
+ * The counter is not exposed over HTTP yet (scope creep). Internal
+ * code reads via `readDeprecationCounters()`.
+ */
+
+const deprecationCallCounters = new Map<string, number>();
+
+export function incrementDeprecationCall(routeLabel: string): void {
+  if (typeof routeLabel !== "string" || routeLabel.length === 0) {
+    throw new Error("incrementDeprecationCall requires a non-empty routeLabel");
+  }
+  const previous = deprecationCallCounters.get(routeLabel) ?? 0;
+  deprecationCallCounters.set(routeLabel, previous + 1);
+}
+
+export function readDeprecationCounters(): Record<string, number> {
+  const snapshot: Record<string, number> = {};
+  for (const [label, count] of deprecationCallCounters) {
+    snapshot[label] = count;
+  }
+  return snapshot;
+}
+
+export function resetDeprecationCounters(): void {
+  deprecationCallCounters.clear();
+}

src/main/api-server/routes-agents.ts

@@ -10,8 +10,15 @@ import {
 } from "../agent-permissions";
 import { resolveApprovalDecision } from "../approval-policy";
 import { shouldAutoApprove } from "../execution-policy";
+import { incrementDeprecationCall } from "./deprecation-counter";
 import { requireParam, type AgentApiServer } from "./server-core";
 
+// C4-followup #3: RFC 8594 deprecation headers for the legacy HTTP hire
+// route. Sunset is the 30-day removal gate — if the counter stays zero
+// through this date, delete the handler.
+const LEGACY_HIRE_ROUTE_LABEL = "POST /api/companies/:companyId/agents";
+const LEGACY_HIRE_SUNSET = new Date("2026-05-20T00:00:00Z").toUTCString();
+
 export function registerAgentRoutes(server: AgentApiServer) {
   const db = server.db;
   const callbacks = server.callbacks;
@@ -106,6 +113,12 @@ export function registerAgentRoutes(server: AgentApiServer) {
    * so residual callers are easy to audit.
    */
   server.addRoute("POST", "/api/companies/:companyId/agents", (_req, res, params, token, body) => {
+    // RFC 8594 deprecation signaling — emit on every response from this
+    // handler regardless of downstream validation outcome.
+    res.setHeader("Deprecation", "true");
+    res.setHeader("Sunset", LEGACY_HIRE_SUNSET);
+    res.setHeader("Link", '</docs/proposals/C4-followup.md>; rel="deprecation"');
+    incrementDeprecationCall(LEGACY_HIRE_ROUTE_LABEL);
     const companyId = requireParam(params, "companyId");
     if (companyId !== token.companyId) {
       server.json(res, 403, { error: "Company mismatch" });

src/main/api-server/routes-approvals.ts

@@ -3,8 +3,16 @@ import log from "electron-log/main.js";
 import { approvalInputSchema } from "@shared/contracts";
 import { resolveApprovalDecision } from "../approval-policy";
 import { shouldAutoApprove } from "../execution-policy";
+import { incrementDeprecationCall } from "./deprecation-counter";
 import { requireParam, type AgentApiServer } from "./server-core";
 
+// C4-followup #3: RFC 8594 deprecation headers for the legacy
+// approve_ceo_strategy HTTP path. Only this approval type is
+// deprecated — other types still use this route as first-class.
+const LEGACY_APPROVE_CEO_STRATEGY_LABEL =
+  "POST /api/companies/:companyId/approvals type=approve_ceo_strategy";
+const LEGACY_APPROVE_CEO_STRATEGY_SUNSET = new Date("2026-05-20T00:00:00Z").toUTCString();
+
 const approvalListQuerySchema = z.object({
   requestedByAgentId: z.string().uuid().optional(),
   relatedTaskId: z.string().uuid().optional(),
@@ -43,6 +51,10 @@ export function registerApprovalRoutes(server: AgentApiServer) {
     }
     const input = parsed.data;
     if (input.type === "approve_ceo_strategy") {
+      res.setHeader("Deprecation", "true");
+      res.setHeader("Sunset", LEGACY_APPROVE_CEO_STRATEGY_SUNSET);
+      res.setHeader("Link", '</docs/proposals/C4-followup.md>; rel="deprecation"');
+      incrementDeprecationCall(LEGACY_APPROVE_CEO_STRATEGY_LABEL);
       log.warn(
         `[deprecated][C4] POST /api/companies/${companyId}/approvals type=approve_ceo_strategy — prefer the file_approval internal tool (caller agent=${token.agentId}).`,
       );