diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 458bb67e0a..261aece1d1 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -67,6 +67,14 @@ jobs:
   bump-dev-version:
     needs: publish
     if: ${{ inputs.dry-run != true }}
+    # A reusable-workflow CALL cannot grant the callee more than the calling job holds,
+    # and GitHub refuses the whole run at startup when the called workflow's own job
+    # declares permissions the caller did not pass down ("startup_failure", runs
+    # 33615174183 / 33615177849 — the first dispatches since #3129 wired this call).
+    # The callee's job declares exactly these two; nothing else in this file gains them.
+    permissions:
+      contents: write
+      pull-requests: write
     uses: ./.github/workflows/dev-version-bump.yml
     with:
       released-version: v${{ inputs.version }}
diff --git a/src/codex/reset-credit-auto-redeem.ts b/src/codex/reset-credit-auto-redeem.ts
index 19b6d3ae0e..d3d365a23b 100644
--- a/src/codex/reset-credit-auto-redeem.ts
+++ b/src/codex/reset-credit-auto-redeem.ts
@@ -1,6 +1,7 @@
 import { createHash, randomUUID } from "node:crypto";
 import { existsSync, readFileSync } from "node:fs";
 import { join } from "node:path";
+import { withConfigMutationLockSync } from "../config";
 import { atomicWriteFile } from "../config/atomic-write";
 import { getConfigDir } from "../config/paths";
 import { registerOptionalShutdownHook } from "../lib/optional-shutdown-hooks";
@@ -118,6 +119,8 @@ export interface AutoRedeemDeps {
   maxSleepMs?: number;
   /** Interval to re-inspect when no credit is due yet (default 30 min). */
   idleRecheckMs?: number;
+  /** @internal Test seam used to synchronize peer processes immediately before journal reservation. */
+  beforeDispatchForTest?: () => Promise<void>;
 }
 
 export type AutoRedeemOutcome =
@@ -156,15 +159,25 @@ export function createResetCreditAutoRedeemer(deps: AutoRedeemDeps): ResetCredit
   };
 
   const dispatch = async (plan: AutoRedeemPlan): Promise<AutoRedeemOutcome> => {
-    const journal = readJournal(path);
-    let entry = journal.entries.find(e => e.accountKey === accountKey && e.grantedAt === plan.grantedAt && e.expiresAt === plan.expiresAt);
-    if (entry?.state === "settled") return { kind: "skipped", reason: "credit-gone" };
-    if (!entry) {
-      entry = { accountKey, grantedAt: plan.grantedAt, expiresAt: plan.expiresAt, redeemRequestId: randomUUID(), state: "dispatched", updatedAt: now() };
-      journal.entries.push(entry);
-      // Journal BEFORE the network call: a crash after this line replays the same request id.
-      writeJournal(path, journal);
+    let entry: JournalEntry;
+    try {
+      entry = withConfigMutationLockSync(() => {
+        const journal = readJournal(path);
+        let reserved = journal.entries.find(e => e.accountKey === accountKey && e.grantedAt === plan.grantedAt && e.expiresAt === plan.expiresAt);
+        if (!reserved) {
+          reserved = { accountKey, grantedAt: plan.grantedAt, expiresAt: plan.expiresAt, redeemRequestId: randomUUID(), state: "dispatched", updatedAt: now() };
+          journal.entries.push(reserved);
+          // Reserve BEFORE the network call. The shared transaction makes minting the
+          // idempotency key atomic across sibling server processes.
+          writeJournal(path, journal);
+        }
+        return reserved;
+      });
+    } catch (error) {
+      schedule(1_000);
+      return { kind: "error", message: error instanceof Error ? error.message : "journal reservation failed" };
     }
+    if (entry.state === "settled") return { kind: "skipped", reason: "credit-gone" };
     log(`[opencodex] reset-credit auto-redeem: dispatching for account ${accountKey} (credit expires ${plan.expiresAt})`);
     let result: { code: string };
     try {
@@ -174,9 +187,22 @@ export function createResetCreditAutoRedeemer(deps: AutoRedeemDeps): ResetCredit
       schedule(60_000);
       return { kind: "ambiguous", redeemRequestId: entry.redeemRequestId };
     }
-    entry.state = "settled";
-    entry.updatedAt = now();
-    writeJournal(path, journal);
+    try {
+      withConfigMutationLockSync(() => {
+        const journal = readJournal(path);
+        const current = journal.entries.find(e => e.accountKey === accountKey && e.grantedAt === plan.grantedAt && e.expiresAt === plan.expiresAt);
+        if (current) {
+          current.state = "settled";
+          current.updatedAt = now();
+          writeJournal(path, journal);
+        }
+      });
+    } catch (error) {
+      // The consume succeeded, so retain the same operation id and retry settlement rather
+      // than allowing a peer to mint a replacement reservation.
+      schedule(1_000);
+      return { kind: "error", message: error instanceof Error ? error.message : "journal settlement failed" };
+    }
     log(`[opencodex] reset-credit auto-redeem: upstream answered ${result.code} for account ${accountKey}`);
     schedule(idleRecheckMs);
     return { kind: "dispatched", code: result.code, redeemRequestId: entry.redeemRequestId };
@@ -206,6 +232,7 @@ export function createResetCreditAutoRedeemer(deps: AutoRedeemDeps): ResetCredit
         return { kind: "error", message: error instanceof Error ? error.message : "inspect failed" } as AutoRedeemOutcome;
       }
       if (!creditStillPresent(fresh, plan)) { schedule(idleRecheckMs); return { kind: "skipped", reason: "credit-gone" } as AutoRedeemOutcome; }
+      await deps.beforeDispatchForTest?.();
       return dispatch(plan);
     })().finally(() => { inFlight = null; });
     return inFlight;
diff --git a/tests/codex-reset-credit-auto-redeem.test.ts b/tests/codex-reset-credit-auto-redeem.test.ts
index 21f651eef9..024e39335e 100644
--- a/tests/codex-reset-credit-auto-redeem.test.ts
+++ b/tests/codex-reset-credit-auto-redeem.test.ts
@@ -1,7 +1,8 @@
 import { afterEach, beforeEach, describe, expect, test } from "bun:test";
-import { mkdtempSync, readFileSync} from "node:fs";
+import { mkdtempSync, readFileSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
+import { pathToFileURL } from "node:url";
 import {
   createResetCreditAutoRedeemer,
   planAutoRedeem,
@@ -141,6 +142,49 @@ describe("reset-credit auto-redeemer runtime (#822)", () => {
     expect(resumed.consumed).toEqual([id]);
   });
 
+  test("sibling processes share one idempotency key for the same credit", async () => {
+    const workers = 8;
+    const journalFile = join(dir, "j.json");
+    const consumeLog = join(dir, "consume.log");
+    const moduleUrl = pathToFileURL(join(import.meta.dir, "../src/codex/reset-credit-auto-redeem.ts")).href;
+    const script = `
+      import { appendFileSync, readdirSync, writeFileSync } from "node:fs";
+      import { join } from "node:path";
+      import { createResetCreditAutoRedeemer } from ${JSON.stringify(moduleUrl)};
+      const [dir, journalFile, consumeLog, worker, count] = process.argv.slice(1);
+      const now = ${T0 + 20 * MIN};
+      const redeemer = createResetCreditAutoRedeemer({
+        accountId: "acct-main",
+        settings: () => ({ enabled: true, leadTimeMinutes: 10 }),
+        inspect: async () => ({ credits: [{ granted_at: "2026-09-01T00:00:00Z", expires_at: "2026-09-02T10:30:00.000Z" }] }),
+        consume: async id => { appendFileSync(consumeLog, id + "\\n"); await Bun.sleep(25); return { code: "reset" }; },
+        now: () => now,
+        setTimer: () => 1,
+        clearTimer: () => {},
+        journalFile,
+        log: () => {},
+        beforeDispatchForTest: async () => {
+          writeFileSync(join(dir, "ready-" + worker), "");
+          while (readdirSync(dir).filter(name => name.startsWith("ready-")).length < Number(count)) await Bun.sleep(1);
+        },
+      });
+      for (;;) {
+        const outcome = await redeemer.tick();
+        if (outcome.kind !== "error") break;
+        await Bun.sleep(2);
+      }
+    `;
+    const children = Array.from({ length: workers }, (_, worker) => Bun.spawn(
+      [process.execPath, "--eval", script, dir, journalFile, consumeLog, String(worker), String(workers)],
+      { env: { ...process.env, OPENCODEX_HOME: dir }, stdout: "pipe", stderr: "pipe" },
+    ));
+    const exits = await Promise.all(children.map(child => child.exited));
+    expect(exits).toEqual(Array(workers).fill(0));
+    const ids = readFileSync(consumeLog, "utf8").trim().split("\n");
+    expect(ids.length).toBeGreaterThan(0);
+    expect(new Set(ids).size).toBe(1);
+  });
+
   test("a manual redeem racing between the planning read and the pre-dispatch read is caught", async () => {
     const journalFile = join(dir, "j.json");
     let reads = 0;