[Bug]: Claude context polluted with model change message every turn on web #1381

claude jsonl session log:
{"type":"queue-operation","operation":"enqueue","timestamp":"2026-03-24T19:40:03.582Z","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9"}
{"type":"queue-operation","operation":"dequeue","timestamp":"2026-03-24T19:40:03.583Z","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9"}
{"parentUuid":null,"isSidechain":false,"promptId":"4e3f2fd3-af80-494e-a194-a0109d461e34","type":"user","message":{"role":"user","content":"<local-command-caveat>Caveat: The messages below were generated by the user while running local commands. DO NOT respond to these messages or otherwise consider them in your response unless the user explicitly asks you to.</local-command-caveat>"},"isMeta":true,"uuid":"8bc63c5a-5e5a-4390-a074-8df6e6831951","timestamp":"2026-03-24T19:40:03.560Z","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}
{"parentUuid":"8bc63c5a-5e5a-4390-a074-8df6e6831951","isSidechain":false,"promptId":"4e3f2fd3-af80-494e-a194-a0109d461e34","type":"user","message":{"role":"user","content":"<command-name>/model</command-name>\n            <command-message>model</command-message>\n            <command-args>claude-sonnet-4-6</command-args>"},"uuid":"288bf7aa-3991-4d21-8be7-a835102fb91c","timestamp":"2026-03-24T19:40:03.560Z","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}
{"parentUuid":"288bf7aa-3991-4d21-8be7-a835102fb91c","isSidechain":false,"promptId":"4e3f2fd3-af80-494e-a194-a0109d461e34","type":"user","message":{"role":"user","content":"<local-command-stdout>Set model to claude-sonnet-4-6</local-command-stdout>"},"uuid":"b151a9a2-b105-497c-8279-11e063702638","timestamp":"2026-03-24T19:40:03.560Z","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}
{"parentUuid":"b151a9a2-b105-497c-8279-11e063702638","isSidechain":false,"promptId":"4e3f2fd3-af80-494e-a194-a0109d461e34","type":"user","message":{"role":"user","content":[{"type":"text","text":"hi"}]},"uuid":"8b59d566-cb10-493f-a6ec-a29d4003fe64","timestamp":"2026-03-24T19:40:03.598Z","permissionMode":"bypassPermissions","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}
{"parentUuid":"8b59d566-cb10-493f-a6ec-a29d4003fe64","isSidechain":false,"message":{"model":"claude-sonnet-4-6","id":"msg_01EpQuEZrx7Po7iCFtrAXKwa","type":"message","role":"assistant","content":[{"type":"text","text":"Hi! How can I help you today?"}],"stop_reason":"end_turn","stop_sequence":null,"usage":{"input_tokens":3,"cache_creation_input_tokens":3938,"cache_read_input_tokens":6212,"output_tokens":12,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":3938,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZNUNUVLTi8RDqvmBXJVS","type":"assistant","uuid":"a1586a24-4433-4aea-b7bd-887fca53aa0b","timestamp":"2026-03-24T19:40:05.431Z","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}
{"type":"queue-operation","operation":"enqueue","timestamp":"2026-03-24T19:40:09.241Z","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9"}
{"type":"queue-operation","operation":"dequeue","timestamp":"2026-03-24T19:40:09.241Z","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9"}
{"parentUuid":"a1586a24-4433-4aea-b7bd-887fca53aa0b","isSidechain":false,"promptId":"8aeb5021-908e-4b10-a973-629b86f546df","type":"user","message":{"role":"user","content":"<local-command-caveat>Caveat: The messages below were generated by the user while running local commands. DO NOT respond to these messages or otherwise consider them in your response unless the user explicitly asks you to.</local-command-caveat>"},"isMeta":true,"uuid":"0a4e061b-3dc1-4dfb-90f4-caaee31a9fe8","timestamp":"2026-03-24T19:40:09.232Z","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}
{"parentUuid":"0a4e061b-3dc1-4dfb-90f4-caaee31a9fe8","isSidechain":false,"promptId":"8aeb5021-908e-4b10-a973-629b86f546df","type":"user","message":{"role":"user","content":"<command-name>/model</command-name>\n            <command-message>model</command-message>\n            <command-args>claude-sonnet-4-6</command-args>"},"uuid":"7d8ca9df-b9e8-43e4-b1b5-33cbce863aa6","timestamp":"2026-03-24T19:40:09.232Z","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}
{"parentUuid":"7d8ca9df-b9e8-43e4-b1b5-33cbce863aa6","isSidechain":false,"promptId":"8aeb5021-908e-4b10-a973-629b86f546df","type":"user","message":{"role":"user","content":"<local-command-stdout>Set model to claude-sonnet-4-6</local-command-stdout>"},"uuid":"cf8ebca9-62ce-4f3a-bb63-3034777f6b05","timestamp":"2026-03-24T19:40:09.232Z","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}
{"parentUuid":"cf8ebca9-62ce-4f3a-bb63-3034777f6b05","isSidechain":false,"promptId":"8aeb5021-908e-4b10-a973-629b86f546df","type":"user","message":{"role":"user","content":[{"type":"text","text":"hi 2"}]},"uuid":"8dfa3c38-3176-46aa-8c6a-13e517470b02","timestamp":"2026-03-24T19:40:09.247Z","permissionMode":"bypassPermissions","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}
{"parentUuid":"8dfa3c38-3176-46aa-8c6a-13e517470b02","isSidechain":false,"message":{"model":"claude-sonnet-4-6","id":"msg_016pf66jCFXgveZKmWfcmej7","type":"message","role":"assistant","content":[{"type":"thinking","thinking":"The user said \"hi 2\". Simple greeting response.","signature":"EtcBCkYIDBgCKkDEMWjEpc73R0xGZSVmSfMyBERV1cWByLD9RyPk+EFNO6ru5M8INq27mg9imGrVKc9Hv90U2+Y+rjHlSEvb8U24EgwqhdHD7G+Z8V1FoUcaDNj7e37t1LFO4jUI6iIwCYDcCHjeGRCCktR7f8j4zLnw6dZK5gFydvpmSIexBFX8biKvqDU5YwjZhztuowpNKj/J6zU1/W05yR9LgmALyzDxkXJZHlBnE/1gbiuGLQH/O5UpHERFpdwUkCUBr3xK0BMk9VAz0jB1mJuBZ8+IoLsYAQ=="}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":3,"cache_creation_input_tokens":143,"cache_read_input_tokens":10150,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":143},"output_tokens":0,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZNUNtavaaWBkvQjuoZ8Z","type":"assistant","uuid":"0b83e5bc-5f6b-4cbe-ba9e-c180ad4dedb2","timestamp":"2026-03-24T19:40:11.694Z","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}
{"parentUuid":"0b83e5bc-5f6b-4cbe-ba9e-c180ad4dedb2","isSidechain":false,"message":{"model":"claude-sonnet-4-6","id":"msg_016pf66jCFXgveZKmWfcmej7","type":"message","role":"assistant","content":[{"type":"text","text":"Hi again! 👋 What's on your mind?"}],"stop_reason":"end_turn","stop_sequence":null,"usage":{"input_tokens":3,"cache_creation_input_tokens":143,"cache_read_input_tokens":10150,"output_tokens":43,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":143,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZNUNtavaaWBkvQjuoZ8Z","type":"assistant","uuid":"4420ddbb-6b57-45c0-8edd-46ef0d94b71a","timestamp":"2026-03-24T19:40:11.701Z","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}
{"type":"queue-operation","operation":"enqueue","timestamp":"2026-03-24T19:40:27.736Z","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9"}
{"type":"queue-operation","operation":"dequeue","timestamp":"2026-03-24T19:40:27.736Z","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9"}
{"parentUuid":"4420ddbb-6b57-45c0-8edd-46ef0d94b71a","isSidechain":false,"promptId":"99c78481-28db-4330-ac8d-21b8469445e0","type":"user","message":{"role":"user","content":"<local-command-caveat>Caveat: The messages below were generated by the user while running local commands. DO NOT respond to these messages or otherwise consider them in your response unless the user explicitly asks you to.</local-command-caveat>"},"isMeta":true,"uuid":"bbb8b9f4-cc88-47ba-bb79-9713e9a09235","timestamp":"2026-03-24T19:40:27.730Z","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}
{"parentUuid":"bbb8b9f4-cc88-47ba-bb79-9713e9a09235","isSidechain":false,"promptId":"99c78481-28db-4330-ac8d-21b8469445e0","type":"user","message":{"role":"user","content":"<command-name>/model</command-name>\n            <command-message>model</command-message>\n            <command-args>claude-sonnet-4-6</command-args>"},"uuid":"45631aab-f6e0-40fc-b2a9-ccac3a0d1d9c","timestamp":"2026-03-24T19:40:27.730Z","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}
{"parentUuid":"45631aab-f6e0-40fc-b2a9-ccac3a0d1d9c","isSidechain":false,"promptId":"99c78481-28db-4330-ac8d-21b8469445e0","type":"user","message":{"role":"user","content":"<local-command-stdout>Set model to claude-sonnet-4-6</local-command-stdout>"},"uuid":"06d3bbed-f69a-49b2-8d41-6a17faeac5de","timestamp":"2026-03-24T19:40:27.730Z","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}
{"parentUuid":"06d3bbed-f69a-49b2-8d41-6a17faeac5de","isSidechain":false,"promptId":"99c78481-28db-4330-ac8d-21b8469445e0","type":"user","message":{"role":"user","content":[{"type":"text","text":"how many times do you see that /model was run?"}]},"uuid":"e2b974e7-2a20-4538-b741-2eee7d0515b0","timestamp":"2026-03-24T19:40:27.739Z","permissionMode":"bypassPermissions","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}
{"parentUuid":"e2b974e7-2a20-4538-b741-2eee7d0515b0","isSidechain":false,"message":{"model":"claude-sonnet-4-6","id":"msg_019kfznEw9ncrRViSsW4Ayzo","type":"message","role":"assistant","content":[{"type":"thinking","thinking":"The user is asking about the /model command. Looking at the conversation, I can see the /model command was run 3 times (once before \"hi\", once before \"hi 2\", and once before this message). However, the caveat says these were generated by the user running local commands and I should NOT respond to these messages unless explicitly asked. The user is now explicitly asking about it, so I can respond.","signature":"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"}],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":3,"cache_creation_input_tokens":183,"cache_read_input_tokens":10293,"cache_creation":{"ephemeral_5m_input_tokens":0,"ephemeral_1h_input_tokens":183},"output_tokens":6,"service_tier":"standard","inference_geo":"not_available"}},"requestId":"req_011CZNUQFfUCeMq1ePeYEmMp","type":"assistant","uuid":"418ac8d6-d701-42f1-85c6-011328fa5a4d","timestamp":"2026-03-24T19:40:30.560Z","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}
{"parentUuid":"418ac8d6-d701-42f1-85c6-011328fa5a4d","isSidechain":false,"message":{"model":"claude-sonnet-4-6","id":"msg_019kfznEw9ncrRViSsW4Ayzo","type":"message","role":"assistant","content":[{"type":"text","text":"I can see the `/model` command was run **3 times** — once before each of your messages (\"hi\", \"hi 2\", and this current message). Each time it set the model to `claude-sonnet-4-6`."}],"stop_reason":"end_turn","stop_sequence":null,"usage":{"input_tokens":3,"cache_creation_input_tokens":183,"cache_read_input_tokens":10293,"output_tokens":158,"server_tool_use":{"web_search_requests":0,"web_fetch_requests":0},"service_tier":"standard","cache_creation":{"ephemeral_1h_input_tokens":183,"ephemeral_5m_input_tokens":0},"inference_geo":"","iterations":[],"speed":"standard"}},"requestId":"req_011CZNUQFfUCeMq1ePeYEmMp","type":"assistant","uuid":"ce2d9769-3897-4715-abc8-823889de2925","timestamp":"2026-03-24T19:40:31.274Z","userType":"external","entrypoint":"sdk-ts","cwd":"/home/user","sessionId":"4583438d-5539-4d73-8785-2503d7f159b9","version":"2.1.81","gitBranch":"HEAD"}