diff --git a/src/codex-warmup.test.ts b/src/codex-warmup.test.ts
index a52c97d..99c3920 100644
--- a/src/codex-warmup.test.ts
+++ b/src/codex-warmup.test.ts
@@ -453,3 +453,115 @@ describe('Codex warm-up scheduler', () => {
     expect(childProcess.spawn).not.toHaveBeenCalled();
   });
 });
+
+describe('Codex warm-up fixed-slot forceAttempt', () => {
+  let tempHome: string;
+  let statePath: string;
+  // Two consecutive slots 5h apart, but the primer fires a beat after the slot,
+  // so the gap is just under minIntervalMs (5h).
+  const t13 = new Date('2026-06-09T04:00:00.486Z').getTime();
+  const t18 = new Date('2026-06-09T09:00:00.000Z').getTime();
+  const config = {
+    enabled: true as const,
+    prompt: 'Reply exactly OK. Do not run tools.',
+    model: 'gpt-5.5',
+    intervalMs: 300_000,
+    minIntervalMs: 18_000_000, // 5h
+    staggerMs: 1_800_000,
+    maxUsagePct: 100,
+    maxD7UsagePct: 100,
+    commandTimeoutMs: 120_000,
+    failureCooldownMs: 21_600_000,
+    maxConsecutiveFailures: 2,
+  };
+
+  beforeEach(() => {
+    vi.resetModules();
+    vi.clearAllMocks();
+    tempHome = fs.mkdtempSync(path.join('/tmp', 'ejclaw-codex-force-'));
+    statePath = path.join(tempHome, 'codex-warmup-state.json');
+    fs.mkdirSync(path.dirname(authPathFor(tempHome, 0)), { recursive: true });
+    fs.writeFileSync(authPathFor(tempHome, 0), '{}');
+  });
+
+  afterEach(() => {
+    fs.rmSync(tempHome, { recursive: true, force: true });
+  });
+
+  async function setup() {
+    const childProcess = await import('child_process');
+    const rotation = await import('./codex-token-rotation.js');
+    const { runCodexWarmupCycle } = await import('./codex-warmup.js');
+    vi.mocked(rotation.getAllCodexAccounts).mockReturnValue([
+      {
+        index: 0,
+        accountId: 'acct',
+        planType: 'pro',
+        isActive: true,
+        isRateLimited: false,
+        cachedUsagePct: 0,
+        cachedUsageD7Pct: 0,
+      },
+    ]);
+    vi.mocked(rotation.getCodexAuthPath).mockImplementation(
+      (accountIndex = 0) => authPathFor(tempHome, accountIndex),
+    );
+    vi.mocked(childProcess.spawn).mockImplementation(
+      (() => createFakeCodexProcess(0) as never) as unknown as typeof childProcess.spawn,
+    );
+    return { childProcess, runCodexWarmupCycle };
+  }
+
+  it('fires at the next slot even when it is just under the 5h min-interval', async () => {
+    const { childProcess, runCodexWarmupCycle } = await setup();
+    const r1 = await runCodexWarmupCycle(config, {
+      nowMs: t13,
+      statePath,
+      ignoreZeroUsageWindow: true,
+      forceAttempt: true,
+    });
+    expect(r1).toEqual({ status: 'warmed', accountIndex: 0 });
+    const r2 = await runCodexWarmupCycle(config, {
+      nowMs: t18,
+      statePath,
+      ignoreZeroUsageWindow: true,
+      forceAttempt: true,
+    });
+    expect(r2).toEqual({ status: 'warmed', accountIndex: 0 });
+    expect(childProcess.spawn).toHaveBeenCalledTimes(2);
+  });
+
+  it('without forceAttempt, the sub-5h second slot is skipped (regression guard)', async () => {
+    const { runCodexWarmupCycle } = await setup();
+    await runCodexWarmupCycle(config, {
+      nowMs: t13,
+      statePath,
+      ignoreZeroUsageWindow: true,
+    });
+    const r2 = await runCodexWarmupCycle(config, {
+      nowMs: t18,
+      statePath,
+      ignoreZeroUsageWindow: true,
+    });
+    expect(r2).toEqual({ status: 'skipped', reason: 'no_eligible_accounts' });
+  });
+
+  it('forceAttempt bypasses post-failure cooldown and stagger', async () => {
+    const { runCodexWarmupCycle } = await setup();
+    fs.writeFileSync(
+      statePath,
+      JSON.stringify({
+        disabledUntil: new Date(t18 + 3_600_000).toISOString(),
+        lastWarmupAt: new Date(t18 - 1_000).toISOString(),
+        accounts: {},
+      }),
+    );
+    const result = await runCodexWarmupCycle(config, {
+      nowMs: t18,
+      statePath,
+      ignoreZeroUsageWindow: true,
+      forceAttempt: true,
+    });
+    expect(result).toEqual({ status: 'warmed', accountIndex: 0 });
+  });
+});
diff --git a/src/codex-warmup.ts b/src/codex-warmup.ts
index 1e336b8..8c0f491 100644
--- a/src/codex-warmup.ts
+++ b/src/codex-warmup.ts
@@ -36,6 +36,15 @@ interface CodexWarmupRuntimeOptions {
   statePath?: string;
   shouldSkip?: () => boolean;
   ignoreZeroUsageWindow?: boolean;
+  /**
+   * Fixed-slot primer mode: bypass the opportunistic warm-up skip gates
+   * (stagger, post-failure cooldown, min-interval, per-account usage/rate-limit
+   * filters) so a real Codex command is attempted at every 08/13/18/23 slot and
+   * its success/failure recorded. Without this, two slots exactly 5h apart fall
+   * just under minIntervalMs (the primer fires a few hundred ms after the slot)
+   * and the later slot is silently skipped as `no_eligible_accounts`.
+   */
+  forceAttempt?: boolean;
 }
 
 export type CodexWarmupCycleResult =
@@ -162,15 +171,20 @@ function selectWarmupCandidate(
   config: CodexWarmupConfig,
   state: CodexWarmupState,
   nowMs: number,
-  options: { ignoreZeroUsageWindow?: boolean } = {},
+  options: { ignoreZeroUsageWindow?: boolean; forceAttempt?: boolean } = {},
 ): { accountIndex: number; zeroUsageWarmupUntil: string } | { reason: string } {
   const disabledUntilMs = parseTimestamp(state.disabledUntil);
-  if (disabledUntilMs != null && disabledUntilMs > nowMs) {
+  if (
+    !options.forceAttempt &&
+    disabledUntilMs != null &&
+    disabledUntilMs > nowMs
+  ) {
     return { reason: 'disabled_cooldown' };
   }
 
   const lastGlobalWarmupMs = parseTimestamp(state.lastWarmupAt);
   if (
+    !options.forceAttempt &&
     lastGlobalWarmupMs != null &&
     config.staggerMs > 0 &&
     nowMs - lastGlobalWarmupMs < config.staggerMs
@@ -181,6 +195,16 @@ function selectWarmupCandidate(
   const accounts = getAllCodexAccounts();
   if (accounts.length === 0) return { reason: 'no_accounts' };
 
+  // Fixed-slot primer: attempt a real command on the active account every slot,
+  // bypassing the per-account usage/rate-limit/min-interval filters below.
+  if (options.forceAttempt) {
+    const active = accounts.find((a) => a.isActive) ?? accounts[0];
+    return {
+      accountIndex: active.index,
+      zeroUsageWarmupUntil: new Date(nowMs).toISOString(),
+    };
+  }
+
   for (const account of accounts) {
     if (account.isRateLimited) continue;
     if (typeof account.cachedUsagePct !== 'number') continue;
@@ -322,6 +346,7 @@ export async function runCodexWarmupCycle(
   const state = readWarmupState(statePath);
   const selected = selectWarmupCandidate(config, state, nowMs, {
     ignoreZeroUsageWindow: runtime.ignoreZeroUsageWindow,
+    forceAttempt: runtime.forceAttempt,
   });
   if ('reason' in selected) {
     return { status: 'skipped', reason: selected.reason };
diff --git a/src/usage-primer.test.ts b/src/usage-primer.test.ts
index 18e649b..feaaa64 100644
--- a/src/usage-primer.test.ts
+++ b/src/usage-primer.test.ts
@@ -71,7 +71,7 @@ describe('usage-primer', () => {
         maxUsagePct: 100,
         maxD7UsagePct: 100,
       }),
-      { ignoreZeroUsageWindow: true },
+      { ignoreZeroUsageWindow: true, forceAttempt: true },
     );
   });
 });
diff --git a/src/usage-primer.ts b/src/usage-primer.ts
index b2e80c4..bb4687e 100644
--- a/src/usage-primer.ts
+++ b/src/usage-primer.ts
@@ -163,7 +163,11 @@ export async function runCodexPrimerCycle(): Promise<void> {
         maxUsagePct: CODEX_PRIMER_MAX_USAGE_PCT,
         maxD7UsagePct: CODEX_PRIMER_MAX_D7_USAGE_PCT,
       },
-      { ignoreZeroUsageWindow: true },
+      // forceAttempt: fire a real Codex command at *every* fixed slot,
+      // bypassing the opportunistic warm-up skip gates. Without it, two slots
+      // exactly 5h apart fall just under minIntervalMs (the primer fires a few
+      // hundred ms after the slot) and the later slot is silently skipped.
+      { ignoreZeroUsageWindow: true, forceAttempt: true },
     );
     // Best-effort: a slot may land while the trailing 5h window is exhausted,
     // in which case this records `failed`. We deliberately do NOT try to