fix(persistence): preserve subagent session origin

examples/acp-agent/tests/snapshots/advanced-toolchain/session.1.jsonl

@@ -1,4 +1,4 @@
-{"type":"session","version":0,"id":"22222222-2222-4222-8222-222222222222","createdAt":1783950001000,"cwd":"{{cwd}}","parentSession":"11111111-1111-4111-8111-111111111111","delegationDepth":1}
+{"type":"session","version":0,"id":"22222222-2222-4222-8222-222222222222","createdAt":1783950001000,"cwd":"{{cwd}}","parentSession":"11111111-1111-4111-8111-111111111111","origin":"subagent","delegationDepth":1}
 {"type":"turn/start","seq":0,"time":1783957884563,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
 {"type":"user/message","seq":1,"time":1783957884563,"data":{"content":[{"type":"text","text":"Reply with exactly DIRECT_CHILD_OK and nothing else."}],"source":{"kind":"user"},"role":"user","id":"9769d9fc-4aef-45ae-bea7-dfa1697971ef"},"surfaceOp":"append"}
 {"type":"session/title","seq":2,"time":1783957884563,"data":{"title":"Reply with exactly DIRECT_CHILD_OK and","messageSeqs":[1],"source":{"kind":"fallback"}}}

examples/acp-agent/tests/snapshots/advanced-toolchain/session.2.jsonl

@@ -1,4 +1,4 @@
-{"type":"session","version":0,"id":"33333333-3333-4333-8333-333333333333","createdAt":1783950002000,"cwd":"{{cwd}}","parentSession":"11111111-1111-4111-8111-111111111111","delegationDepth":1}
+{"type":"session","version":0,"id":"33333333-3333-4333-8333-333333333333","createdAt":1783950002000,"cwd":"{{cwd}}","parentSession":"11111111-1111-4111-8111-111111111111","origin":"subagent","delegationDepth":1}
 {"type":"turn/start","seq":0,"time":1783957884700,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
 {"type":"user/message","seq":1,"time":1783957884700,"data":{"content":[{"type":"text","text":"Reply with exactly WORKFLOW_CHILD_OK and nothing else."}],"source":{"kind":"user"},"role":"user","id":"a9ccad1e-ded5-4f5f-9419-a6bc440e96c3"},"surfaceOp":"append"}
 {"type":"session/title","seq":2,"time":1783957884700,"data":{"title":"Reply with exactly WORKFLOW_CHILD_OK and","messageSeqs":[1],"source":{"kind":"fallback"}}}

examples/acp-agent/tests/snapshots/subagent-continuable/session.1.jsonl

@@ -1,4 +1,4 @@
-{"type":"session","version":0,"id":"33333333-3333-4333-8333-333333333333","createdAt":1789000001000,"cwd":"{{cwd}}","parentSession":"11111111-1111-4111-8111-111111111111","delegationDepth":1}
+{"type":"session","version":0,"id":"33333333-3333-4333-8333-333333333333","createdAt":1789000001000,"cwd":"{{cwd}}","parentSession":"11111111-1111-4111-8111-111111111111","origin":"subagent","delegationDepth":1}
 {"type":"subagent/descriptor","seq":0,"time":1785544945198,"data":{"version":2,"mode":"continuable","provider":"spawn","label":"Reply with CHILD_OK","agentProvider":"deepseek-official","agentModel":"deepseek-v4-flash"}}
 {"type":"session/end-seed","seq":1,"time":1785544945198,"data":{}}
 {"type":"turn/start","seq":2,"time":1785544945199,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}

examples/acp-agent/tests/snapshots/subagent-depth-two-rejection/session.1.jsonl

@@ -1,4 +1,4 @@
-{"type":"session","version":0,"id":"22222222-2222-4222-8222-222222222222","createdAt":1001,"cwd":"{{cwd}}","parentSession":"11111111-1111-4111-8111-111111111111","delegationDepth":1}
+{"type":"session","version":0,"id":"22222222-2222-4222-8222-222222222222","createdAt":1001,"cwd":"{{cwd}}","parentSession":"11111111-1111-4111-8111-111111111111","origin":"subagent","delegationDepth":1}
 {"type":"turn/start","seq":0,"time":1784540790312,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
 {"type":"user/message","seq":1,"time":1784540790312,"data":{"content":[{"type":"text","text":"Call subagent once. Ask that child to attempt one further subagent call, then report the result."}],"source":{"kind":"user"},"role":"user","id":"9cf268f7-2c64-4344-8512-dc9cb4dc66d4"},"surfaceOp":"append"}
 {"type":"session/title","seq":2,"time":1784540790312,"data":{"title":"Call subagent once. Ask that","messageSeqs":[1],"source":{"kind":"fallback"}}}

examples/acp-agent/tests/snapshots/subagent-depth-two-rejection/session.2.jsonl

@@ -1,4 +1,4 @@
-{"type":"session","version":0,"id":"33333333-3333-4333-8333-333333333333","createdAt":1002,"cwd":"{{cwd}}","parentSession":"22222222-2222-4222-8222-222222222222","delegationDepth":2}
+{"type":"session","version":0,"id":"33333333-3333-4333-8333-333333333333","createdAt":1002,"cwd":"{{cwd}}","parentSession":"22222222-2222-4222-8222-222222222222","origin":"subagent","delegationDepth":2}
 {"type":"turn/start","seq":0,"time":1784540790319,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
 {"type":"user/message","seq":1,"time":1784540790319,"data":{"content":[{"type":"text","text":"Attempt one subagent call beyond the configured cap, then report the rejection."}],"source":{"kind":"user"},"role":"user","id":"17f4fd95-842c-4c48-90d9-cdd04456687f"},"surfaceOp":"append"}
 {"type":"session/title","seq":2,"time":1784540790319,"data":{"title":"Attempt one subagent call beyond","messageSeqs":[1],"source":{"kind":"fallback"}}}

examples/acp-agent/tests/snapshots/subagent-fork/session.1.jsonl

@@ -1,4 +1,4 @@
-{"type":"session","version":0,"id":"ada8966c-9fa3-441b-8721-37ff1e795e6a","createdAt":1783352137161,"cwd":"{{cwd}}","parentSession":"96cf59c9-b347-48b9-b234-a5200913ad05","seedLength":40,"delegationDepth":1}
+{"type":"session","version":0,"id":"ada8966c-9fa3-441b-8721-37ff1e795e6a","createdAt":1783352137161,"cwd":"{{cwd}}","parentSession":"96cf59c9-b347-48b9-b234-a5200913ad05","seedLength":40,"origin":"subagent","delegationDepth":1}
 {"type":"turn/start","seq":0,"time":1783352134837,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
 {"type":"user/message","seq":1,"time":1783352134838,"data":{"content":[{"type":"text","text":"Remember this fact for later: the project codeword is MARMALADE. Reply with the single word OK and stop. Do not use any tools."}],"source":{"kind":"user"},"role":"user","id":"181ef004-8be2-416c-a223-3ff7f99cc79c"},"surfaceOp":"append"}
 {"type":"session/title","seq":2,"time":1783352134838,"data":{"title":"Remember this fact for later:","messageSeqs":[1],"source":{"kind":"fallback"}}}

examples/acp-agent/tests/snapshots/subagent-list-agents/session.1.jsonl

@@ -1,4 +1,4 @@
-{"type":"session","version":0,"id":"33333333-3333-4333-8333-333333333333","createdAt":1789000001000,"cwd":"{{cwd}}","parentSession":"11111111-1111-4111-8111-111111111111","delegationDepth":1}
+{"type":"session","version":0,"id":"33333333-3333-4333-8333-333333333333","createdAt":1789000001000,"cwd":"{{cwd}}","parentSession":"11111111-1111-4111-8111-111111111111","origin":"subagent","delegationDepth":1}
 {"type":"subagent/descriptor","seq":0,"time":1785531795641,"data":{"version":2,"mode":"continuable","provider":"spawn","label":"Reply with CHILD_OK","agentProvider":"deepseek-official","agentModel":"deepseek-v4-flash"}}
 {"type":"session/end-seed","seq":1,"time":1785531795641,"data":{}}
 {"type":"turn/start","seq":2,"time":1785531795641,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}

examples/acp-agent/tests/snapshots/subagent-mixed/session.1.jsonl

@@ -1,4 +1,4 @@
-{"type":"session","version":0,"id":"e4aafa18-b9e3-48d0-8aae-6c9b25dcae80","createdAt":1783352145223,"cwd":"{{cwd}}","parentSession":"959ffdf5-03e2-465e-9482-009b704632dc","delegationDepth":1}
+{"type":"session","version":0,"id":"e4aafa18-b9e3-48d0-8aae-6c9b25dcae80","createdAt":1783352145223,"cwd":"{{cwd}}","parentSession":"959ffdf5-03e2-465e-9482-009b704632dc","origin":"subagent","delegationDepth":1}
 {"type":"turn/start","seq":0,"time":1783352145224,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
 {"type":"user/message","seq":1,"time":1783352145224,"data":{"content":[{"type":"text","text":"Reply with exactly the word ALPHA and nothing else."}],"source":{"kind":"user"},"role":"user","id":"ad85672f-96fe-4462-a2c7-0411ab9c92c2"},"surfaceOp":"append"}
 {"type":"session/title","seq":2,"time":1783352145224,"data":{"title":"Reply with exactly the word","messageSeqs":[1],"source":{"kind":"fallback"}}}

examples/acp-agent/tests/snapshots/subagent-mixed/session.2.jsonl

@@ -1,4 +1,4 @@
-{"type":"session","version":0,"id":"02b3a8dd-1d5e-4866-825f-5fbf5000a632","createdAt":1783352147504,"cwd":"{{cwd}}","parentSession":"959ffdf5-03e2-465e-9482-009b704632dc","seedLength":34,"delegationDepth":1}
+{"type":"session","version":0,"id":"02b3a8dd-1d5e-4866-825f-5fbf5000a632","createdAt":1783352147504,"cwd":"{{cwd}}","parentSession":"959ffdf5-03e2-465e-9482-009b704632dc","seedLength":34,"origin":"subagent","delegationDepth":1}
 {"type":"turn/start","seq":0,"time":1783352142834,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
 {"type":"user/message","seq":1,"time":1783352142834,"data":{"content":[{"type":"text","text":"Remember this fact for later: the project codeword is SAFFRON. Reply with the single word OK and stop. Do not use any tools."}],"source":{"kind":"user"},"role":"user","id":"7d598287-d208-4f2d-a97b-66f397094c6c"},"surfaceOp":"append"}
 {"type":"session/title","seq":2,"time":1783352142834,"data":{"title":"Remember this fact for later:","messageSeqs":[1],"source":{"kind":"fallback"}}}

examples/acp-agent/tests/snapshots/subagent-multi/session.1.jsonl

@@ -1,4 +1,4 @@
-{"type":"session","version":0,"id":"553f8e92-aac1-4df3-8657-eacbb58f9581","createdAt":1783352127669,"cwd":"{{cwd}}","parentSession":"14dda109-5728-45ba-a002-7db9543fe50e","delegationDepth":1}
+{"type":"session","version":0,"id":"553f8e92-aac1-4df3-8657-eacbb58f9581","createdAt":1783352127669,"cwd":"{{cwd}}","parentSession":"14dda109-5728-45ba-a002-7db9543fe50e","origin":"subagent","delegationDepth":1}
 {"type":"turn/start","seq":0,"time":1783352127670,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
 {"type":"user/message","seq":1,"time":1783352127670,"data":{"content":[{"type":"text","text":"Reply with exactly the word ALPHA and nothing else."}],"source":{"kind":"user"},"role":"user","id":"78174c9e-c9f2-4c05-8dc4-12108419e6ad"},"surfaceOp":"append"}
 {"type":"session/title","seq":2,"time":1783352127670,"data":{"title":"Reply with exactly the word","messageSeqs":[1],"source":{"kind":"fallback"}}}

examples/acp-agent/tests/snapshots/subagent-multi/session.2.jsonl

@@ -1,4 +1,4 @@
-{"type":"session","version":0,"id":"5f49e80c-16fc-42c7-a617-0b6bd0680aa3","createdAt":1783352129662,"cwd":"{{cwd}}","parentSession":"14dda109-5728-45ba-a002-7db9543fe50e","delegationDepth":1}
+{"type":"session","version":0,"id":"5f49e80c-16fc-42c7-a617-0b6bd0680aa3","createdAt":1783352129662,"cwd":"{{cwd}}","parentSession":"14dda109-5728-45ba-a002-7db9543fe50e","origin":"subagent","delegationDepth":1}
 {"type":"turn/start","seq":0,"time":1783352129662,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
 {"type":"user/message","seq":1,"time":1783352129662,"data":{"content":[{"type":"text","text":"Reply with exactly the word BETA and nothing else."}],"source":{"kind":"user"},"role":"user","id":"9542fa06-afea-4f6d-9db1-b6848def4bc7"},"surfaceOp":"append"}
 {"type":"session/title","seq":2,"time":1783352129662,"data":{"title":"Reply with exactly the word","messageSeqs":[1],"source":{"kind":"fallback"}}}

examples/acp-agent/tests/snapshots/subagent-spawn/session.1.jsonl

@@ -1,4 +1,4 @@
-{"type":"session","version":0,"id":"ea339828-7885-42e1-9083-4355e6f1708d","createdAt":1783352120855,"cwd":"{{cwd}}","parentSession":"5138ed0d-e86e-4a7d-b75b-803307e92b17","delegationDepth":1}
+{"type":"session","version":0,"id":"ea339828-7885-42e1-9083-4355e6f1708d","createdAt":1783352120855,"cwd":"{{cwd}}","parentSession":"5138ed0d-e86e-4a7d-b75b-803307e92b17","origin":"subagent","delegationDepth":1}
 {"type":"turn/start","seq":0,"time":1783352120856,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
 {"type":"user/message","seq":1,"time":1783352120856,"data":{"content":[{"type":"text","text":"Reply with exactly the word CHILD_OK and nothing else."}],"source":{"kind":"user"},"role":"user","id":"c7b8251e-05a6-48da-b7e1-00612d1679a4"},"surfaceOp":"append"}
 {"type":"session/title","seq":2,"time":1783352120856,"data":{"title":"Reply with exactly the word","messageSeqs":[1],"source":{"kind":"fallback"}}}

examples/acp-agent/tests/snapshots/workflow-run/session.1.jsonl

@@ -1,4 +1,4 @@
-{"type":"session","version":0,"id":"583a4db2-3350-436c-b4a5-5615fd159052","createdAt":1783600636316,"cwd":"{{cwd}}","parentSession":"3fd7d599-56b1-493a-930d-f1fc5e1556e8","delegationDepth":1}
+{"type":"session","version":0,"id":"583a4db2-3350-436c-b4a5-5615fd159052","createdAt":1783600636316,"cwd":"{{cwd}}","parentSession":"3fd7d599-56b1-493a-930d-f1fc5e1556e8","origin":"subagent","delegationDepth":1}
 {"type":"turn/start","seq":0,"time":1783600636316,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
 {"type":"user/message","seq":1,"time":1783600636316,"data":{"content":[{"type":"text","text":"Reply with exactly the word WF_CHILD_OK and nothing else."}],"source":{"kind":"user"},"role":"user","id":"a7990b4d-9b1d-47de-883b-47f6755c2b9b"},"surfaceOp":"append"}
 {"type":"session/title","seq":2,"time":1783600636316,"data":{"title":"Reply with exactly the word","messageSeqs":[1],"source":{"kind":"fallback"}}}

examples/headless-agent/tests/subagent-inheritance-snapshots/parent-override/child.expected.jsonl

@@ -1,4 +1,4 @@
-{"type":"session","version":0,"id":"{{sessionId}}","createdAt":0,"cwd":"{{cwd}}","parentSession":"{{sessionId}}","delegationDepth":1}
+{"type":"session","version":0,"id":"{{sessionId}}","createdAt":0,"cwd":"{{cwd}}","parentSession":"{{sessionId}}","origin":"subagent","delegationDepth":1}
 {"type":"sandbox/mode","seq":0,"time":0,"data":{"mode":"read-only","source":"delegation"}}
 {"type":"turn/start","seq":1,"time":0,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
 {"type":"user/message","seq":2,"time":0,"data":{"content":[{"type":"text","text":"Use the write tool exactly once with file_path set to exactly the relative path inherited.txt and content escaped. If the write is denied, reply with the single word CHILD_DENIED and the denial marker line; do not retry and do not request escalation. If it succeeds, reply CHILD_WROTE."}],"source":{"kind":"user"},"role":"user","id":"{{sessionId}}"},"surfaceOp":"append"}

examples/jsonrpc-agent/tests/snapshots/subagent-spawn/session.1.jsonl

@@ -1,4 +1,4 @@
-{"type":"session","version":0,"id":"0b7fd85c-9f6f-4d46-b954-363984ce66fb","createdAt":1785097410282,"cwd":"{{cwd}}","parentSession":"sdk-snapshot-subagent","delegationDepth":1}
+{"type":"session","version":0,"id":"0b7fd85c-9f6f-4d46-b954-363984ce66fb","createdAt":1785097410282,"cwd":"{{cwd}}","parentSession":"sdk-snapshot-subagent","origin":"subagent","delegationDepth":1}
 {"type":"turn/start","seq":0,"time":1785097410283,"data":{"turn":1,"trigger":{"kind":"message","source":{"kind":"user"}}}}
 {"type":"user/message","seq":1,"time":1785097410283,"data":{"content":[{"type":"text","text":"Reply with exactly: child answer 42."}],"source":{"kind":"user"},"role":"user","id":"b33e0611-0483-44a9-8b57-9828b87cb846"},"surfaceOp":"append"}
 {"type":"session/title","seq":2,"time":1785097410283,"data":{"title":"Reply with exactly: child answer","messageSeqs":[1],"source":{"kind":"fallback"}}}