fix(server): Codex forks no longer request the full thread history

apps/server/scripts/record-codex-app-server-replay-fixture.ts

@@ -1431,6 +1431,7 @@ const runReplaySession = Effect.fn("record-codex-app-server-replay-fixture.runRe
           const lastTurnId = lastTurnIdByThread.get(sourceThreadId);
           const forked = yield* client.request("thread/fork", {
             threadId: sourceThreadId,
+            excludeTurns: true,
             ...(lastTurnId === undefined ? {} : { lastTurnId }),
             ...threadRuntimeParams,
           });

apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.test.ts

@@ -6606,7 +6606,11 @@ describe("CodexAdapterV2 post-settle continuation", () => {
               frame: {
                 id: 3,
                 method: "thread/fork",
-                params: { threadId: nativeThreadId, config: CodexAdapterV2.CODEX_THREAD_CONFIG },
+                params: {
+                  threadId: nativeThreadId,
+                  excludeTurns: true,
+                  config: CodexAdapterV2.CODEX_THREAD_CONFIG,
+                },
               },
             },
             {
@@ -6729,6 +6733,83 @@ describe("CodexAdapterV2 post-settle continuation", () => {
       ),
   );
 
+  it.effect("forks at a native turn without asking Codex for the historical turns", () =>
+    Effect.gen(function* () {
+      const nativeThreadId = "exclude-turns-source-thread";
+      const forkThreadId = "exclude-turns-fork-thread";
+      const preamble = codexReplayPreamble({
+        nativeThreadId,
+        nativeTurnId: "exclude-turns-source-turn",
+        prompt: "unused",
+      });
+      // Replay matches the whole outbound frame, so a fork request that omits
+      // `excludeTurns` (the full-history payload that overran the transport
+      // limit) fails here instead of reaching a real app-server.
+      const transcript = makeCodexReplayTranscript({
+        scenario: "codex-fork-exclude-turns",
+        entries: [
+          ...preamble.slice(0, 5),
+          {
+            type: "expect_outbound",
+            label: "thread/fork",
+            frame: {
+              id: 3,
+              method: "thread/fork",
+              params: {
+                threadId: nativeThreadId,
+                lastTurnId: "native-turn-first",
+                excludeTurns: true,
+                config: CodexAdapterV2.CODEX_THREAD_CONFIG,
+              },
+            },
+          },
+          {
+            type: "emit_inbound",
+            label: "thread/fork",
+            frame: {
+              id: 3,
+              result: codexReplayThreadResult({
+                nativeThreadId: forkThreadId,
+                forkedFromId: nativeThreadId,
+              }),
+            },
+          },
+        ],
+      });
+      const harness = yield* makeCodexReplayHarness(transcript);
+      const now = yield* DateTime.now;
+      const firstTurn = codexReplaySourceTurn({
+        id: "provider-turn-first",
+        ordinal: 1,
+        nativeId: "native-turn-first",
+        providerThreadId: harness.providerThread.id,
+        now,
+      });
+      const secondTurn = codexReplaySourceTurn({
+        id: "provider-turn-second",
+        ordinal: 2,
+        nativeId: "native-turn-second",
+        providerThreadId: harness.providerThread.id,
+        now,
+      });
+
+      const forkedProviderThread = yield* harness.runtime.forkThread({
+        sourceProviderThread: harness.providerThread,
+        sourceProviderTurns: [firstTurn, secondTurn],
+        providerTurnId: firstTurn.id,
+        targetThreadId: ThreadId.make("thread-fork-exclude-turns-target"),
+      });
+
+      assert.equal(forkedProviderThread.nativeThreadRef?.nativeId, forkThreadId);
+      assert.equal(forkedProviderThread.forkedFrom?.providerTurnId, firstTurn.id);
+    }).pipe(
+      Effect.scoped,
+      Effect.provide(
+        Layer.mergeAll(IdAllocator.layer, McpProviderSessions.layer, NodeServices.layer),
+      ),
+    ),
+  );
+
   describe("native goals", () => {
     const nativeThreadId = "goal-thread";
     const objective = "Ship the feature";

apps/server/src/orchestration-v2/Adapters/CodexAdapterV2.ts

@@ -7640,6 +7640,10 @@ export const makeCodexAdapterV2 = Effect.fn("makeCodexAdapterV2")(function* (
                 Effect.andThen(
                   client.request("thread/fork", {
                     threadId,
+                    // The adapter only needs thread metadata; without this the
+                    // response carries the whole history, which overruns the
+                    // transport limit on very large threads.
+                    excludeTurns: true,
                     ...(boundary.lastTurnId === undefined
                       ? {}
                       : { lastTurnId: boundary.lastTurnId }),

apps/server/src/orchestration-v2/testkit/fixtures/thread_fork_native_prior_turn/codex_transcript.ndjson

@@ -48,7 +48,7 @@
 {"type":"emit_inbound","label":"account/rateLimits/updated","frame":{"method":"account/rateLimits/updated","params":{"rateLimits":{"limitId":"codex","limitName":null,"primary":{"usedPercent":61,"windowDurationMins":300,"resetsAt":1777429830},"secondary":{"usedPercent":23,"windowDurationMins":10080,"resetsAt":1777959590},"credits":null,"planType":"unknown","rateLimitReachedType":null}}}}
 {"type":"emit_inbound","label":"thread/status/changed","frame":{"method":"thread/status/changed","params":{"threadId":"019dd6ba-2681-7bf0-b051-141b0cbcbb27","status":{"type":"idle"}}}}
 {"type":"emit_inbound","label":"turn/completed","frame":{"method":"turn/completed","params":{"threadId":"019dd6ba-2681-7bf0-b051-141b0cbcbb27","turn":{"id":"019dd6ba-416d-7902-95cf-d4179c3f4738","items":[],"status":"completed","error":null,"startedAt":1777424023,"completedAt":1777424025,"durationMs":1596}}}}
-{"type":"expect_outbound","label":"thread/fork","frame":{"id":5,"method":"thread/fork","params":{"threadId":"019dd6ba-2681-7bf0-b051-141b0cbcbb27","lastTurnId":"019dd6ba-268b-7f82-8f4c-9fde0edcfd55","config":{"tools.update_plan.enabled":true,"mcp_optional_startup_grace_ms":10000}}}}
+{"type":"expect_outbound","label":"thread/fork","frame":{"id":5,"method":"thread/fork","params":{"threadId":"019dd6ba-2681-7bf0-b051-141b0cbcbb27","lastTurnId":"019dd6ba-268b-7f82-8f4c-9fde0edcfd55","excludeTurns":true,"config":{"tools.update_plan.enabled":true,"mcp_optional_startup_grace_ms":10000}}}}
 {"type":"emit_inbound","label":"deprecationNotice","frame":{"method":"deprecationNotice","params":{"summary":"`[features].collab` is deprecated. Use `[features].multi_agent` instead.","details":"Enable it with `--enable multi_agent` or `[features].multi_agent` in config.toml. See https://developers.openai.com/codex/config-basic#feature-flags for details."}}}
 {"type":"emit_inbound","label":"warning","frame":{"method":"warning","params":{"threadId":"019dd6ba-47b7-7092-8688-9cf7fe5f6498","message":"Under-development features enabled: apply_patch_freeform. Under-development features are incomplete and may behave unpredictably. To suppress this warning, set `suppress_unstable_features_warning = true` in /home/replay-user/.codex/config.toml."}}}
 {"type":"emit_inbound","label":"mcpServer/startupStatus/updated","frame":{"method":"mcpServer/startupStatus/updated","params":{"name":"uidotsh","status":"starting","error":null}}}

apps/server/src/orchestration-v2/testkit/fixtures/thread_merge_back_siblings/codex_transcript.ndjson

@@ -27,7 +27,7 @@
 {"type":"emit_inbound","label":"thread/tokenUsage/updated","frame":{"method":"thread/tokenUsage/updated","params":{"threadId":"01a0d610-155f-7391-843e-120bf1475357","turnId":"01a0d610-1619-7d91-bae2-ec4a7b899193","tokenUsage":{"total":{"totalTokens":17752,"inputTokens":17744,"cachedInputTokens":14848,"cacheWriteInputTokens":0,"outputTokens":8,"reasoningOutputTokens":0},"last":{"totalTokens":17752,"inputTokens":17744,"cachedInputTokens":14848,"cacheWriteInputTokens":0,"outputTokens":8,"reasoningOutputTokens":0},"modelContextWindow":258400}},"emittedAtMs":1790297778003}}
 {"type":"emit_inbound","label":"thread/status/changed","frame":{"method":"thread/status/changed","params":{"threadId":"01a0d610-155f-7391-843e-120bf1475357","status":{"type":"idle"}},"emittedAtMs":1790297778011}}
 {"type":"emit_inbound","label":"turn/completed","frame":{"method":"turn/completed","params":{"threadId":"01a0d610-155f-7391-843e-120bf1475357","turn":{"id":"01a0d610-1619-7d91-bae2-ec4a7b899193","items":[{"type":"agentMessage","id":"msg_0c4d0b070a58ed52016ab5c6b1b0fc87d0a540ea4be4112eb0","text":"merge sibling source stored","phase":"final_answer","memoryCitation":null,"delivery":null,"questions":null}],"itemsView":"summary","status":"completed","error":null,"startedAt":1790297773,"completedAt":1790297778,"durationMs":4400}},"emittedAtMs":1790297778011}}
-{"type":"expect_outbound","label":"thread/fork","frame":{"id":4,"method":"thread/fork","params":{"config":{"tools.update_plan.enabled":true,"mcp_optional_startup_grace_ms":10000},"cwd":"<workspace>","lastTurnId":"01a0d610-1619-7d91-bae2-ec4a7b899193","model":"gpt-6-sol","threadId":"01a0d610-155f-7391-843e-120bf1475357"}}}
+{"type":"expect_outbound","label":"thread/fork","frame":{"id":4,"method":"thread/fork","params":{"config":{"tools.update_plan.enabled":true,"mcp_optional_startup_grace_ms":10000},"cwd":"<workspace>","excludeTurns":true,"lastTurnId":"01a0d610-1619-7d91-bae2-ec4a7b899193","model":"gpt-6-sol","threadId":"01a0d610-155f-7391-843e-120bf1475357"}}}
 {"type":"emit_inbound","label":"deprecationNotice","frame":{"method":"deprecationNotice","params":{"summary":"Full-history hydration is deprecated for paginated threads; use `excludeTurns: true`, then page with `thread/turns/list` and `thread/items/list`.","details":null},"emittedAtMs":1790297778016}}
 {"type":"emit_inbound","label":"mcpServer/startupStatus/updated","frame":{"method":"mcpServer/startupStatus/updated","params":{"threadId":"01a0d610-155f-7391-843e-120bf1475357","name":"xcodebuildmcp","status":"ready","error":null,"failureReason":null},"emittedAtMs":1790297778263}}
 {"type":"emit_inbound","label":"mcpServer/startupStatus/updated","frame":{"method":"mcpServer/startupStatus/updated","params":{"threadId":"01a0d610-2789-7bb3-a492-ad7fa8a7db9c","name":"codex_apps","status":"starting","error":null,"failureReason":null},"emittedAtMs":1790297778313}}
@@ -52,7 +52,7 @@
 {"type":"emit_inbound","label":"thread/tokenUsage/updated","frame":{"method":"thread/tokenUsage/updated","params":{"threadId":"01a0d610-2789-7bb3-a492-ad7fa8a7db9c","turnId":"01a0d610-28ad-7071-82a1-f55ea8178ae8","tokenUsage":{"total":{"totalTokens":39723,"inputTokens":39707,"cachedInputTokens":26624,"cacheWriteInputTokens":0,"outputTokens":16,"reasoningOutputTokens":0},"last":{"totalTokens":21971,"inputTokens":21963,"cachedInputTokens":11776,"cacheWriteInputTokens":0,"outputTokens":8,"reasoningOutputTokens":0},"modelContextWindow":258400}},"emittedAtMs":1790297782125}}
 {"type":"emit_inbound","label":"thread/status/changed","frame":{"method":"thread/status/changed","params":{"threadId":"01a0d610-2789-7bb3-a492-ad7fa8a7db9c","status":{"type":"idle"}},"emittedAtMs":1790297782161}}
 {"type":"emit_inbound","label":"turn/completed","frame":{"method":"turn/completed","params":{"threadId":"01a0d610-2789-7bb3-a492-ad7fa8a7db9c","turn":{"id":"01a0d610-28ad-7071-82a1-f55ea8178ae8","items":[{"type":"agentMessage","id":"msg_0c4d0b070a58ed52016ab5c6b5b44c87d08e7e5612c5312499","text":"first merge sibling stored","phase":"final_answer","memoryCitation":null,"delivery":null,"questions":null}],"itemsView":"summary","status":"completed","error":null,"startedAt":1790297778,"completedAt":1790297782,"durationMs":3783}},"emittedAtMs":1790297782161}}
-{"type":"expect_outbound","label":"thread/fork","frame":{"id":6,"method":"thread/fork","params":{"config":{"tools.update_plan.enabled":true,"mcp_optional_startup_grace_ms":10000},"cwd":"<workspace>","lastTurnId":"01a0d610-1619-7d91-bae2-ec4a7b899193","model":"gpt-6-sol","threadId":"01a0d610-155f-7391-843e-120bf1475357"}}}
+{"type":"expect_outbound","label":"thread/fork","frame":{"id":6,"method":"thread/fork","params":{"config":{"tools.update_plan.enabled":true,"mcp_optional_startup_grace_ms":10000},"cwd":"<workspace>","excludeTurns":true,"lastTurnId":"01a0d610-1619-7d91-bae2-ec4a7b899193","model":"gpt-6-sol","threadId":"01a0d610-155f-7391-843e-120bf1475357"}}}
 {"type":"emit_inbound","label":"deprecationNotice","frame":{"method":"deprecationNotice","params":{"summary":"Full-history hydration is deprecated for paginated threads; use `excludeTurns: true`, then page with `thread/turns/list` and `thread/items/list`.","details":null},"emittedAtMs":1790297782170}}
 {"type":"emit_inbound","label":"mcpServer/startupStatus/updated","frame":{"method":"mcpServer/startupStatus/updated","params":{"threadId":"01a0d610-37d1-7ba1-918f-136cfdbd9bfd","name":"xcodebuildmcp","status":"starting","error":null,"failureReason":null},"emittedAtMs":1790297782559}}
 {"type":"emit_inbound","label":"mcpServer/startupStatus/updated","frame":{"method":"mcpServer/startupStatus/updated","params":{"threadId":"01a0d610-37d1-7ba1-918f-136cfdbd9bfd","name":"codex_apps","status":"starting","error":null,"failureReason":null},"emittedAtMs":1790297782559}}