{ "note": "Sanitized cache-session receipts: one CLI process per session, 2 turns each, a seeded synthetic ledger (a different seed per condition) and 2 short questions with exact answers. Conditions: A a new temporary working folder per session, B one fixed folder, C a fixed folder with the ledger in the system prompt (Claude Code only). The Codex app-server reports cached input only, so its rows have no cache-write count. Probes are single uncounted calls with their own ledger seed. The answers and the ledger itself are not published. Session 1 was the first use of each setup’s ledger; sessions 2 and 3 reused that ledger. Different seeds prevent full ledger-prefix reuse between setups, but shared CLI-prefix reads remain possible. Correctness uses the reference checker after it trims spaces, surrounding quotes and backticks, a final period and currency units. The surviving protocol file dates from after the counted calls; pre-call declaration is not verified.", "study": "prompt-cache-across-sessions", "conditions": [ { "id": "A", "label": "A: a new temporary working folder for every session, ledger in the first user message", "cwdMode": "new-per-session", "ledgerIn": "user-message", "ledgerChars": 9600 }, { "id": "B", "label": "B: one fixed working folder, ledger in the first user message", "cwdMode": "fixed", "ledgerIn": "user-message", "ledgerChars": 9565 }, { "id": "C", "label": "C: one fixed working folder, ledger in the system prompt", "cwdMode": "fixed", "ledgerIn": "system-prompt", "ledgerChars": 9588 } ], "batches": [ { "batch": "batch-1", "route": "claude-cli", "cliVersion": "2.1.286", "startedAt": "2026-10-07T00:32:33.401Z", "finishedAt": "2026-10-07T00:33:04.274Z", "calls": 18, "trimmed": 0, "stopReason": null, "sessions": [ { "condition": "A", "session": 1, "status": "completed", "startedAt": "2026-10-07T00:32:33.402Z", "gapBetweenCallsMs": null, "modelReported": "claude-sonnet-5-5", "effort": "default", "turns": [ { "turn": 1, "startedAt": "2026-10-07T00:32:33.628Z", "status": "completed", "correct": true, "firstUsefulMs": 1330, "totalMs": 1344, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 531, "cacheWriteTokens": 7320, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 7320, "outputTokens": 3, "thinkingTokens": 0 }, "rateLimitStatus": "allowed_warning" }, { "turn": 2, "startedAt": "2026-10-07T00:32:34.973Z", "status": "completed", "correct": true, "firstUsefulMs": 862, "totalMs": 875, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 7851, "cacheWriteTokens": 58, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 58, "outputTokens": 5, "thinkingTokens": 0 }, "rateLimitStatus": null } ] }, { "condition": "A", "session": 2, "status": "completed", "startedAt": "2026-10-07T00:32:36.367Z", "gapBetweenCallsMs": 720, "modelReported": "claude-sonnet-5-5", "effort": "default", "turns": [ { "turn": 1, "startedAt": "2026-10-07T00:32:36.568Z", "status": "completed", "correct": true, "firstUsefulMs": 1534, "totalMs": 1556, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 1463, "cacheWriteTokens": 6386, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 6386, "outputTokens": 3, "thinkingTokens": 0 }, "rateLimitStatus": "allowed_warning" }, { "turn": 2, "startedAt": "2026-10-07T00:32:38.125Z", "status": "completed", "correct": true, "firstUsefulMs": 1131, "totalMs": 1143, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 7849, "cacheWriteTokens": 58, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 58, "outputTokens": 5, "thinkingTokens": 0 }, "rateLimitStatus": null } ] }, { "condition": "A", "session": 3, "status": "completed", "startedAt": "2026-10-07T00:32:39.603Z", "gapBetweenCallsMs": 528, "modelReported": "claude-sonnet-5-5", "effort": "default", "turns": [ { "turn": 1, "startedAt": "2026-10-07T00:32:39.796Z", "status": "completed", "correct": true, "firstUsefulMs": 1606, "totalMs": 1618, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 1463, "cacheWriteTokens": 6388, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 6388, "outputTokens": 3, "thinkingTokens": 0 }, "rateLimitStatus": "allowed_warning" }, { "turn": 2, "startedAt": "2026-10-07T00:32:41.415Z", "status": "completed", "correct": true, "firstUsefulMs": 1010, "totalMs": 1023, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 7851, "cacheWriteTokens": 58, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 58, "outputTokens": 5, "thinkingTokens": 0 }, "rateLimitStatus": null } ] }, { "condition": "B", "session": 1, "status": "completed", "startedAt": "2026-10-07T00:32:42.816Z", "gapBetweenCallsMs": null, "modelReported": "claude-sonnet-5-5", "effort": "default", "turns": [ { "turn": 1, "startedAt": "2026-10-07T00:32:43.012Z", "status": "completed", "correct": true, "firstUsefulMs": 1846, "totalMs": 1855, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 1463, "cacheWriteTokens": 6370, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 6370, "outputTokens": 3, "thinkingTokens": 0 }, "rateLimitStatus": "allowed_warning" }, { "turn": 2, "startedAt": "2026-10-07T00:32:44.867Z", "status": "completed", "correct": true, "firstUsefulMs": 1314, "totalMs": 1329, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 7833, "cacheWriteTokens": 58, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 58, "outputTokens": 6, "thinkingTokens": 0 }, "rateLimitStatus": null } ] }, { "condition": "B", "session": 2, "status": "completed", "startedAt": "2026-10-07T00:32:46.526Z", "gapBetweenCallsMs": 511, "modelReported": "claude-sonnet-5-5", "effort": "default", "turns": [ { "turn": 1, "startedAt": "2026-10-07T00:32:46.707Z", "status": "completed", "correct": true, "firstUsefulMs": 1702, "totalMs": 1711, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 7833, "cacheWriteTokens": 0, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 0, "outputTokens": 3, "thinkingTokens": 0 }, "rateLimitStatus": "allowed_warning" }, { "turn": 2, "startedAt": "2026-10-07T00:32:48.418Z", "status": "completed", "correct": true, "firstUsefulMs": 1353, "totalMs": 1365, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 7891, "cacheWriteTokens": 0, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 0, "outputTokens": 6, "thinkingTokens": 0 }, "rateLimitStatus": null } ] }, { "condition": "B", "session": 3, "status": "completed", "startedAt": "2026-10-07T00:32:50.099Z", "gapBetweenCallsMs": 508, "modelReported": "claude-sonnet-5-5", "effort": "default", "turns": [ { "turn": 1, "startedAt": "2026-10-07T00:32:50.292Z", "status": "completed", "correct": true, "firstUsefulMs": 1749, "totalMs": 1761, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 7833, "cacheWriteTokens": 0, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 0, "outputTokens": 3, "thinkingTokens": 0 }, "rateLimitStatus": "allowed_warning" }, { "turn": 2, "startedAt": "2026-10-07T00:32:52.053Z", "status": "completed", "correct": true, "firstUsefulMs": 1301, "totalMs": 1313, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 7891, "cacheWriteTokens": 0, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 0, "outputTokens": 6, "thinkingTokens": 0 }, "rateLimitStatus": null } ] }, { "condition": "C", "session": 1, "status": "completed", "startedAt": "2026-10-07T00:32:53.706Z", "gapBetweenCallsMs": null, "modelReported": "claude-sonnet-5-5", "effort": "default", "turns": [ { "turn": 1, "startedAt": "2026-10-07T00:32:53.895Z", "status": "completed", "correct": true, "firstUsefulMs": 1674, "totalMs": 1688, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 540, "cacheWriteTokens": 7275, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 7275, "outputTokens": 3, "thinkingTokens": 0 }, "rateLimitStatus": "allowed_warning" }, { "turn": 2, "startedAt": "2026-10-07T00:32:55.583Z", "status": "completed", "correct": true, "firstUsefulMs": 1275, "totalMs": 1289, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 7815, "cacheWriteTokens": 58, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 58, "outputTokens": 5, "thinkingTokens": 0 }, "rateLimitStatus": null } ] }, { "condition": "C", "session": 2, "status": "completed", "startedAt": "2026-10-07T00:32:57.249Z", "gapBetweenCallsMs": 593, "modelReported": "claude-sonnet-5-5", "effort": "default", "turns": [ { "turn": 1, "startedAt": "2026-10-07T00:32:57.465Z", "status": "completed", "correct": true, "firstUsefulMs": 1773, "totalMs": 1781, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 7815, "cacheWriteTokens": 0, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 0, "outputTokens": 3, "thinkingTokens": 0 }, "rateLimitStatus": "allowed_warning" }, { "turn": 2, "startedAt": "2026-10-07T00:32:59.247Z", "status": "completed", "correct": true, "firstUsefulMs": 1070, "totalMs": 1085, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 7873, "cacheWriteTokens": 0, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 0, "outputTokens": 5, "thinkingTokens": 0 }, "rateLimitStatus": null } ] }, { "condition": "C", "session": 3, "status": "completed", "startedAt": "2026-10-07T00:33:00.815Z", "gapBetweenCallsMs": 688, "modelReported": "claude-sonnet-5-5", "effort": "default", "turns": [ { "turn": 1, "startedAt": "2026-10-07T00:33:01.020Z", "status": "completed", "correct": true, "firstUsefulMs": 1759, "totalMs": 1766, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 7815, "cacheWriteTokens": 0, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 0, "outputTokens": 3, "thinkingTokens": 0 }, "rateLimitStatus": "allowed_warning" }, { "turn": 2, "startedAt": "2026-10-07T00:33:02.786Z", "status": "completed", "correct": true, "firstUsefulMs": 1118, "totalMs": 1132, "apiRequests": 1, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 7873, "cacheWriteTokens": 0, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 0, "outputTokens": 5, "thinkingTokens": 0 }, "rateLimitStatus": null } ] } ] }, { "batch": "batch-2", "route": "codex-cli", "cliVersion": "codex-cli 0.160.0", "startedAt": "2026-10-07T00:34:06.243Z", "finishedAt": "2026-10-07T00:34:40.689Z", "calls": 12, "trimmed": 0, "stopReason": null, "sessions": [ { "condition": "A", "session": 1, "status": "completed", "startedAt": "2026-10-07T00:34:06.244Z", "gapBetweenCallsMs": null, "modelReported": "gpt-6.1-sol", "effort": "medium", "turns": [ { "turn": 1, "startedAt": "2026-10-07T00:34:06.766Z", "status": "completed", "correct": true, "firstUsefulMs": 2698, "totalMs": 2767, "usage": { "inputTokensInclCached": 16049, "cachedInputTokens": 4864, "outputTokens": 5, "reasoningTokens": 0 } }, { "turn": 2, "startedAt": "2026-10-07T00:34:09.534Z", "status": "completed", "correct": true, "firstUsefulMs": 1477, "totalMs": 1548, "usage": { "inputTokensInclCached": 16078, "cachedInputTokens": 15872, "outputTokens": 5, "reasoningTokens": 0 } } ] }, { "condition": "A", "session": 2, "status": "completed", "startedAt": "2026-10-07T00:34:11.083Z", "gapBetweenCallsMs": 507, "modelReported": "gpt-6.1-sol", "effort": "medium", "turns": [ { "turn": 1, "startedAt": "2026-10-07T00:34:11.588Z", "status": "completed", "correct": true, "firstUsefulMs": 3948, "totalMs": 3980, "usage": { "inputTokensInclCached": 16051, "cachedInputTokens": 8960, "outputTokens": 5, "reasoningTokens": 0 } }, { "turn": 2, "startedAt": "2026-10-07T00:34:15.569Z", "status": "completed", "correct": true, "firstUsefulMs": 1569, "totalMs": 1647, "usage": { "inputTokensInclCached": 16080, "cachedInputTokens": 15872, "outputTokens": 5, "reasoningTokens": 0 } } ] }, { "condition": "A", "session": 3, "status": "completed", "startedAt": "2026-10-07T00:34:17.217Z", "gapBetweenCallsMs": 581, "modelReported": "gpt-6.1-sol", "effort": "medium", "turns": [ { "turn": 1, "startedAt": "2026-10-07T00:34:17.797Z", "status": "completed", "correct": true, "firstUsefulMs": 4020, "totalMs": 4129, "usage": { "inputTokensInclCached": 16053, "cachedInputTokens": 0, "outputTokens": 5, "reasoningTokens": 0 } }, { "turn": 2, "startedAt": "2026-10-07T00:34:21.926Z", "status": "completed", "correct": true, "firstUsefulMs": 1593, "totalMs": 1681, "usage": { "inputTokensInclCached": 16082, "cachedInputTokens": 15872, "outputTokens": 5, "reasoningTokens": 0 } } ] }, { "condition": "B", "session": 1, "status": "completed", "startedAt": "2026-10-07T00:34:23.608Z", "gapBetweenCallsMs": null, "modelReported": "gpt-6.1-sol", "effort": "medium", "turns": [ { "turn": 1, "startedAt": "2026-10-07T00:34:24.171Z", "status": "completed", "correct": true, "firstUsefulMs": 2491, "totalMs": 2560, "usage": { "inputTokensInclCached": 16033, "cachedInputTokens": 0, "outputTokens": 5, "reasoningTokens": 0 } }, { "turn": 2, "startedAt": "2026-10-07T00:34:26.731Z", "status": "completed", "correct": true, "firstUsefulMs": 1464, "totalMs": 1536, "usage": { "inputTokensInclCached": 16062, "cachedInputTokens": 15872, "outputTokens": 5, "reasoningTokens": 0 } } ] }, { "condition": "B", "session": 2, "status": "completed", "startedAt": "2026-10-07T00:34:28.268Z", "gapBetweenCallsMs": 555, "modelReported": "gpt-6.1-sol", "effort": "medium", "turns": [ { "turn": 1, "startedAt": "2026-10-07T00:34:28.822Z", "status": "completed", "correct": true, "firstUsefulMs": 2784, "totalMs": 2822, "usage": { "inputTokensInclCached": 16033, "cachedInputTokens": 8960, "outputTokens": 5, "reasoningTokens": 0 } }, { "turn": 2, "startedAt": "2026-10-07T00:34:31.644Z", "status": "completed", "correct": true, "firstUsefulMs": 1508, "totalMs": 1580, "usage": { "inputTokensInclCached": 16062, "cachedInputTokens": 15872, "outputTokens": 5, "reasoningTokens": 0 } } ] }, { "condition": "B", "session": 3, "status": "completed", "startedAt": "2026-10-07T00:34:33.225Z", "gapBetweenCallsMs": 633, "modelReported": "gpt-6.1-sol", "effort": "medium", "turns": [ { "turn": 1, "startedAt": "2026-10-07T00:34:33.858Z", "status": "completed", "correct": true, "firstUsefulMs": 3863, "totalMs": 3933, "usage": { "inputTokensInclCached": 16033, "cachedInputTokens": 0, "outputTokens": 5, "reasoningTokens": 0 } }, { "turn": 2, "startedAt": "2026-10-07T00:34:37.791Z", "status": "completed", "correct": true, "firstUsefulMs": 2792, "totalMs": 2898, "usage": { "inputTokensInclCached": 16062, "cachedInputTokens": 15872, "outputTokens": 5, "reasoningTokens": 0 } } ] } ] } ], "probes": [ { "probe": "probe-1", "route": "claude-cli", "startedAt": "2026-10-07T00:32:13.061Z", "condition": "probe", "cwdMode": "fixed", "ledgerIn": "system-prompt", "status": "completed", "correct": true, "totalMs": 1590, "usage": { "uncachedInputTokens": 2, "cacheReadTokens": 540, "cacheWriteTokens": 7274, "cacheWrite5mTokens": 0, "cacheWrite1hTokens": 7274, "outputTokens": 3, "thinkingTokens": 0 } }, { "probe": "probe-2", "route": "codex-cli", "startedAt": "2026-10-07T00:33:57.134Z", "condition": "probe", "cwdMode": "fixed", "ledgerIn": "user-message", "status": "completed", "correct": true, "totalMs": 4721, "usage": { "inputTokensInclCached": 16036, "cachedInputTokens": 8960, "outputTokens": 5, "reasoningTokens": 0 } } ], "audit": { "protocolClaimedDeclarationUtc": "2026-10-07T00:32:00.000Z", "protocolFileBirthUtc": "2026-10-07T00:49:27.076Z", "protocolFileModifiedUtc": "2026-10-07T07:40:42.329Z", "firstCountedCallUtc": "2026-10-07T00:32:33.628Z", "amendment1ClaimedUtc": "2026-10-07T00:36:00.000Z", "amendment2ClaimedUtc": "2026-10-07T00:37:00.000Z", "summaryGeneratedAt": "2026-10-07T07:41:03.477Z", "preCallProtocolVerified": false, "note": "The surviving protocol file was created after all counted calls. No separate pre-edit amendment copies verify the claimed amendment times. File times do not prove whether an earlier copy existed. The current summary was regenerated later. Treat the analysis as exploratory.", "caps": { "claudeCounted": 18, "codexCounted": 12, "probesPerRoute": 1 }, "codexGate": { "optionalHalfWeeklyLeftPct": 30, "batchGateWeeklyLeftPct": 20, "scriptWeeklyLeftPct": 20, "retainedGateReceipt": false } }, "controls": { "generatedAt": "2026-10-07T00:49:43.125Z", "note": "Run after the counted calls. The correctness flag is reported next to the cache numbers; no cache measure depends on it.", "conditions": { "P": { "questions": [ { "question": "q1-qty", "referencePasses": true, "plantedWrongAnswers": 4, "allWrongFail": true }, { "question": "q2-warehouse", "referencePasses": true, "plantedWrongAnswers": 5, "allWrongFail": true } ] }, "A": { "questions": [ { "question": "q1-qty", "referencePasses": true, "plantedWrongAnswers": 4, "allWrongFail": true }, { "question": "q2-warehouse", "referencePasses": true, "plantedWrongAnswers": 5, "allWrongFail": true } ] }, "B": { "questions": [ { "question": "q1-qty", "referencePasses": true, "plantedWrongAnswers": 4, "allWrongFail": true }, { "question": "q2-warehouse", "referencePasses": true, "plantedWrongAnswers": 5, "allWrongFail": true } ] }, "C": { "questions": [ { "question": "q1-qty", "referencePasses": true, "plantedWrongAnswers": 4, "allWrongFail": true }, { "question": "q2-warehouse", "referencePasses": true, "plantedWrongAnswers": 5, "allWrongFail": true } ] } }, "allPass": true } }