diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
index 71f14c14a9..ae2c27bce7 100644
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -1,11 +1,11 @@
 # Default reviewers
-* @lidge-jun @Ingwannu @Wibias
+* @lidge-jun @Ingwannu
 
 # High-impact runtime behavior
-/src/adapters/ @lidge-jun @Ingwannu @Wibias
-/src/providers/ @lidge-jun @Ingwannu @Wibias
-/src/codex/ @lidge-jun @Ingwannu @Wibias
-/src/server/ @lidge-jun @Ingwannu @Wibias
+/src/adapters/ @lidge-jun @Ingwannu
+/src/providers/ @lidge-jun @Ingwannu
+/src/codex/ @lidge-jun @Ingwannu
+/src/server/ @lidge-jun @Ingwannu
 
 # Repository automation and release security
 /.github/ @lidge-jun @Ingwannu
diff --git a/MAINTAINERS.md b/MAINTAINERS.md
index 3214adfdf1..43377c093d 100644
--- a/MAINTAINERS.md
+++ b/MAINTAINERS.md
@@ -9,7 +9,6 @@ review and merge policy.
 | --- | --- | --- |
 | [@lidge-jun](https://github.com/lidge-jun) | Project owner | Project direction, releases, repository administration, and final governance decisions |
 | [@Ingwannu](https://github.com/Ingwannu) | Maintainer | Issue and pull-request triage, `dev` integration, security review, and repository maintenance |
-| [@Wibias](https://github.com/Wibias) | Maintainer | Issue and pull-request triage, `dev` integration, and provider/CI maintenance |
 
 The table describes project responsibilities. Actual repository permissions remain controlled
 through GitHub repository settings.
@@ -17,6 +16,16 @@ through GitHub repository settings.
 `dev` is the only integration line. The former `dev2-go` carry duty is retired;
 see [The retired `dev2-go` line](#the-retired-dev2-go-line).
 
+## Former maintainers
+
+| GitHub account | Project role | Period |
+| --- | --- | --- |
+| [@Wibias](https://github.com/Wibias) | Maintainer | 2026-07-27 – 2026-08-19 |
+
+Former maintainers keep contributor standing and are welcome to open issues and pull requests like
+anyone else. Authorship credit in git history, release notes, and code comments is not rewritten
+when a maintainer steps down.
+
 ## Review and merge policy
 
 - Pull requests target `dev`. It is the only integration line, and promotion to
@@ -98,6 +107,24 @@ Adding or removing a maintainer requires:
 
 ### Change log
 
+- 2026-08-19 — [@Wibias](https://github.com/Wibias) stepped down as a maintainer
+  and is now a contributor. This follows his own decision to stop developing
+  opencodex; it is not a disciplinary action, and it was made with the owner's
+  agreement (requirement 1). Requirement 2 does not apply to a maintainer's own
+  resignation, which needs no second maintainer to ratify it. Requirement 3 is
+  met by this file and `.github/CODEOWNERS`, where the default-reviewer line
+  and the four runtime paths that listed him (`/src/adapters/`,
+  `/src/providers/`, `/src/codex/`, `/src/server/`) drop back to the two
+  remaining maintainers. Repository permission was reduced to read access at
+  the same time, so the roster and the GitHub settings agree again.
+
+  Nothing he authored is being unwound. His commits, the pull requests he
+  merged, the release-note attributions, and the code comments citing his
+  reviews stay exactly as they are, and the trust-lane gate derived from his
+  work in `.github/scripts/pr-sponsored-surface.cjs` keeps its attribution.
+  Returning to the maintainer table later would go through the same three
+  requirements that govern every addition.
+
 - 2026-07-27 — [@Wibias](https://github.com/Wibias) added as a maintainer.
   Requirement 1 (agreement from the project owner) is met: the owner requested
   the addition. **Requirement 2 (review by another current maintainer) was
@@ -105,10 +132,10 @@ Adding or removing a maintainer requires:
   carried the addition (`a2693c02`, `dc3a4ade`, `02bbd47a`) landed on `dev` as
   direct owner pushes with no associated pull request, so no second maintainer
   reviewed them. Requirement 3 is met by this file and `.github/CODEOWNERS`.
-  The addition is in effect regardless: @Wibias holds write access on the
-  repository and has been merging pull requests since 2026-07-26. This entry
-  records the gap rather than papering over it — a later maintainer change
-  should go through a reviewed pull request.
+  The addition took effect regardless: @Wibias held write access on the
+  repository and merged pull requests from 2026-07-26 until he stepped down on
+  2026-08-19. This entry records the gap rather than papering over it — a later
+  maintainer change should go through a reviewed pull request.
 
   Scope covers issue and pull-request triage, `dev` integration, and
   provider/CI maintenance. (This entry originally also described carrying
diff --git a/src/server/responses/core.ts b/src/server/responses/core.ts
index 8d2906e536..7cb2bbb0a7 100644
--- a/src/server/responses/core.ts
+++ b/src/server/responses/core.ts
@@ -2438,13 +2438,13 @@ async function handleResponsesInner(
     // call it cannot execute, and the turn showed a bare `aborted` with the file untouched.
     // Forward auth is the canonical ChatGPT backend speaking Codex's own protocol rather than a
     // routed provider, so it keeps passing through unguarded, as it does for the rewrites above.
-    // The guard needs a catalog to compare against, so it stands down when the request carries
-    // none. That is not the same claim as "no tools means no tool may be called": a passthrough
-    // request can legitimately omit `tools` entirely and still receive a tool call the client
-    // understands — `tests/github-copilot-stream-contract.test.ts` sends `{model, input, stream}`
-    // with no tools and Copilot answers with a `custom_tool_call` for `apply_patch`. Policing an
-    // empty catalog truncates that turn. An unreadable body lands here too, since it yields no
-    // names either.
+    // The guard needs a catalog to compare against, so it stands down when the request omits one.
+    // An explicit empty catalog is still authoritative: it declares that no client tools may be
+    // called. A passthrough request can legitimately omit `tools` entirely and still receive a call
+    // the client understands — `tests/github-copilot-stream-contract.test.ts` sends
+    // `{model, input, stream}` with no tools and Copilot answers with a `custom_tool_call` for
+    // `apply_patch`. Policing an absent catalog truncates that turn. An unreadable body lands there
+    // too because the proxy cannot establish the caller's declared authorization boundary.
     const outboundRequestBody = (() => {
       try {
         const body = JSON.parse(request.body) as unknown;
@@ -2460,7 +2460,9 @@ async function handleResponsesInner(
     // the client's name back. Widening only ever makes the guard fire less; a name declared in
     // neither place — #1700's `apply_patch` — is still refused.
     for (const name of toolBridgeMaps.declaredToolNames) declaredWireToolNames.add(name);
-    const undeclaredToolGuardActive = declaredWireToolNames.size > 0
+    const hasExplicitWireToolCatalog = outboundRequestBody !== undefined
+      && Array.isArray((outboundRequestBody as Record<string, unknown>).tools);
+    const undeclaredToolGuardActive = (declaredWireToolNames.size > 0 || hasExplicitWireToolCatalog)
       && route.provider.authMode !== "forward";
     // A refused turn must not seed `previous_response_id` replay. The inspection branch reads the
     // untouched upstream stream, so it can still observe a `response.completed` the client never
diff --git a/tests/responses-undeclared-tool-guard.test.ts b/tests/responses-undeclared-tool-guard.test.ts
index 3cf8a08e17..01c7542b2a 100644
--- a/tests/responses-undeclared-tool-guard.test.ts
+++ b/tests/responses-undeclared-tool-guard.test.ts
@@ -462,7 +462,7 @@ describe("a refused turn does not become continuation state", () => {
   });
 });
 
-describe("a request that declares no tools has no catalog to police", () => {
+describe("empty and absent tool catalogs", () => {
   const config = {
     port: 0,
     defaultProvider: "fixture",
@@ -520,25 +520,39 @@ describe("a request that declares no tools has no catalog to police", () => {
 
   // A passthrough request may omit `tools` entirely and still receive a tool call the client
   // understands — the Copilot contract in tests/github-copilot-stream-contract.test.ts does
-  // exactly that with `apply_patch`. Refusing on an empty catalog truncates those turns, so the
-  // guard needs at least one declared name before it has an opinion.
-  for (const [label, tools] of [["no tools field", undefined], ["tools: []", []]] as const) {
-    test(`non-streaming, ${label} — relayed, not refused`, async () => {
-      const response = await post(false, tools, jsonUpstream);
-
-      expect(response.status).toBe(200);
-      const body = await response.json() as { output: Array<Record<string, unknown>> };
-      expect(body.output[0]).toMatchObject({ name: "apply_patch" });
-    });
+  // exactly that with `apply_patch`. With no catalog the proxy has no authorization boundary to
+  // enforce, so the call remains untouched on both transports.
+  test("non-streaming, no tools field — relayed, not refused", async () => {
+    const response = await post(false, undefined, jsonUpstream);
 
-    test(`streaming, ${label} — relayed, not refused`, async () => {
-      const response = await post(true, tools, sseUpstream);
-      const body = await response.text();
+    expect(response.status).toBe(200);
+    const body = await response.json() as { output: Array<Record<string, unknown>> };
+    expect(body.output[0]).toMatchObject({ name: "apply_patch" });
+  });
 
-      expect(body).not.toContain(UNDECLARED_TOOL_CALL_ERROR_CODE);
-      expect(body).toContain("response.completed");
-    });
-  }
+  test("streaming, no tools field — relayed, not refused", async () => {
+    const response = await post(true, undefined, sseUpstream);
+    const body = await response.text();
+
+    expect(body).not.toContain(UNDECLARED_TOOL_CALL_ERROR_CODE);
+    expect(body).toContain("response.completed");
+  });
+
+  test("non-streaming, tools: [] — refuses an upstream client tool call", async () => {
+    const response = await post(false, [], jsonUpstream);
+
+    expect(response.status).toBe(502);
+    const body = await response.json() as { error: { message: string } };
+    expect(body.error.message).toContain('undeclared client tool "apply_patch"');
+  });
+
+  test("streaming, tools: [] — refuses an upstream client tool call", async () => {
+    const response = await post(true, [], sseUpstream);
+    const body = await response.text();
+
+    expect(body).toContain(UNDECLARED_TOOL_CALL_ERROR_CODE);
+    expect(body).not.toContain("response.completed");
+  });
 });
 
 describe("undeclaredToolCallNameInResponse", () => {