diff --git a/packages/test-support/session-snapshot/tests/fixtures/record-suite/rec-child/behavior.json b/packages/test-support/session-snapshot/tests/fixtures/record-suite/rec-child/behavior.json
index dbcef3b7c6..13b61ecd39 100644
--- a/packages/test-support/session-snapshot/tests/fixtures/record-suite/rec-child/behavior.json
+++ b/packages/test-support/session-snapshot/tests/fixtures/record-suite/rec-child/behavior.json
@@ -4,196 +4,23 @@
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-            "id": "11111111-1111-4111-8111-111111111111"
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-          "surfaceOp": "append"
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+        {"type":"session","version":2,"id":"{{SID}}","createdAt":700,"cwd":"{{CWD}}","isSeeded":false,"delegationDepth":0},
+        {"type":"turn/start","seq":0,"time":2,"data":{"turn":1}},
+        {"type":"step/start","seq":1,"time":3,"data":{"turn":1,"step":1}},
+        {"type":"system/message","seq":2,"time":3,"data":{"turn":1,"step":1,"message":{"id":"aaaaaaaa-aaaa-4aaa-8aaa-aaaaaaaaaa2","role":"system","content":[{"type":"text","text":"SYS PROMPT"}],"source":{"kind":"plugin","plugin":"@deepseek-ai/dsh-system-prompt"}}},"surfaceOp":"append"},
+        {"type":"request/header","seq":3,"time":3,"data":{"header":{"config":{"provider":"fake","model":"fake"},"tools":[{"name":"t1","description":"D1","parameters":{"type":"object"}}]},"reason":"initial"}},
+        {"type":"user/message","seq":4,"time":5,"data":{"role":"user","content":[{"type":"text","text":"same inherited message"}],"source":{"kind":"user"},"id":"11111111-1111-4111-8111-111111111111"},"surfaceOp":"append"}
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+        {"type":"session","version":2,"id":"abababab-cdcd-4efe-8ada-badabadabada","createdAt":800,"cwd":"{{CWD}}","parentSession":"{{SID}}","isSeeded":false,"delegationDepth":1},
+        {"type":"turn/start","seq":0,"time":1,"data":{"turn":1}},
+        {"type":"step/start","seq":1,"time":2,"data":{"turn":1,"step":1}},
+        {"type":"system/message","seq":2,"time":2,"data":{"turn":1,"step":1,"message":{"id":"aaaaaaaa-aaaa-4aaa-8aaa-aaaaaaaaaa2","role":"system","content":[{"type":"text","text":"SYS PROMPT"}],"source":{"kind":"plugin","plugin":"@deepseek-ai/dsh-system-prompt"}}},"surfaceOp":"append"},
+        {"type":"request/header","seq":3,"time":2,"data":{"header":{"config":{"provider":"fake","model":"fake"},"tools":[{"name":"t1","description":"D1","parameters":{"type":"object"}}]},"reason":"initial"}},
+        {"type":"user/message","seq":4,"time":5,"data":{"role":"user","content":[{"type":"text","text":"same inherited message"}],"source":{"kind":"user"},"id":"11111111-1111-4111-8111-111111111111"},"surfaceOp":"append"}
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diff --git a/packages/test-support/session-snapshot/tests/fixtures/record-suite/rec-pin/behavior.json b/packages/test-support/session-snapshot/tests/fixtures/record-suite/rec-pin/behavior.json
index cc420e2b77..cd695e1f9b 100644
--- a/packages/test-support/session-snapshot/tests/fixtures/record-suite/rec-pin/behavior.json
+++ b/packages/test-support/session-snapshot/tests/fixtures/record-suite/rec-pin/behavior.json
@@ -4,79 +4,11 @@
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+        {"type":"session","version":2,"id":"{{SID}}","createdAt":600,"cwd":"{{CWD}}","isSeeded":false,"delegationDepth":0},
+        {"type":"turn/start","seq":0,"time":3,"data":{"turn":1}},
+        {"type":"step/start","seq":1,"time":4,"data":{"turn":1,"step":1}},
+        {"type":"system/message","seq":2,"time":4,"data":{"turn":1,"step":1,"message":{"id":"aaaaaaaa-aaaa-4aaa-8aaa-aaaaaaaaaaaa","role":"system","content":[{"type":"text","text":"SYS PROMPT"}],"source":{"kind":"plugin","plugin":"@deepseek-ai/dsh-system-prompt"}}},"surfaceOp":"append"},
+        {"type":"request/header","seq":3,"time":4,"data":{"header":{"config":{"provider":"fake","model":"fake"},"tools":[{"name":"t1","description":"D1","parameters":{"type":"object"}}]},"reason":"initial"}}
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diff --git a/packages/test-support/session-snapshot/tests/fixtures/suite/pin-turn/behavior.json b/packages/test-support/session-snapshot/tests/fixtures/suite/pin-turn/behavior.json
index 6a2bc335f5..dc97c64e86 100644
--- a/packages/test-support/session-snapshot/tests/fixtures/suite/pin-turn/behavior.json
+++ b/packages/test-support/session-snapshot/tests/fixtures/suite/pin-turn/behavior.json
@@ -4,172 +4,15 @@
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+        {"type":"session","version":2,"id":"{{SID}}","createdAt":100,"cwd":"{{CWD}}","isSeeded":false,"delegationDepth":0},
+        {"type":"turn/start","seq":0,"time":100,"data":{"turn":1}},
+        {"type":"step/start","seq":1,"time":100,"data":{"turn":1,"step":1}},
+        {"type":"system/message","seq":2,"time":100,"data":{"turn":1,"step":1,"message":{"id":"aaaaaaaa-aaaa-4aaa-8aaa-aaaaaaaaaaaa","role":"system","content":[{"type":"text","text":"SYS PROMPT"}],"source":{"kind":"plugin","plugin":"@deepseek-ai/dsh-system-prompt"}}},"surfaceOp":"append"},
+        {"type":"request/header","seq":3,"time":100,"data":{"header":{"config":{"provider":"fake","model":"fake"},"tools":[{"name":"t1","description":"D1","parameters":{"type":"object"}}]},"reason":"initial"}},
+        {"type":"step/start","seq":4,"time":100,"data":{"turn":1,"step":2}},
+        {"type":"system/message","seq":5,"time":100,"data":{"turn":1,"step":2,"message":{"id":"bbbbbbbb-bbbb-4bbb-8bbb-bbbbbbbbbbbb","role":"system","content":[{"type":"text","text":"SYS PROMPT\n\nNEW PROMPT LINE"}],"source":{"kind":"plugin","plugin":"@deepseek-ai/dsh-system-prompt"}}},"surfaceOp":{"op":"replace","start":2,"end":2},"sourceEventSeqs":[2]},
+        {"type":"request/header","seq":6,"time":100,"data":{"header":{"config":{"provider":"fake","model":"fake"},"tools":[{"name":"t1","description":"D1","parameters":{"type":"object"}}]},"reason":"series"}},
+        {"type":"request/header","seq":7,"time":100,"data":{"header":{"config":{"provider":"fake","model":"fake"},"tools":[{"name":"t1","description":"D1","parameters":{"type":"object"}},{"name":"t2","description":"D2","parameters":{"type":"object"}}]},"reason":"change"}}
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diff --git a/packages/test-support/session-snapshot/tests/fixtures/suite/plain-turn/behavior.json b/packages/test-support/session-snapshot/tests/fixtures/suite/plain-turn/behavior.json
index ce46e9a9a8..8debb01182 100644
--- a/packages/test-support/session-snapshot/tests/fixtures/suite/plain-turn/behavior.json
+++ b/packages/test-support/session-snapshot/tests/fixtures/suite/plain-turn/behavior.json
@@ -5,178 +5,22 @@
     {
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       "lines": [
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-                "index": 0,
-                "dt": [],
-                "texts": [
-                  "hi"
-                ]
-              }
-            ]
-          }
-        }
+        {"type":"session","version":2,"id":"{{SID}}","createdAt":200,"cwd":"{{CWD}}","isSeeded":false,"delegationDepth":0},
+        {"type":"turn/start","seq":0,"time":4,"data":{"turn":1}},
+        {"type":"step/start","seq":1,"time":5,"data":{"turn":1,"step":1}},
+        {"type":"system/message","seq":2,"time":5,"data":{"turn":1,"step":1,"message":{"id":"aaaaaaaa-aaaa-4aaa-8aaa-aaaaaaaaaaaa","role":"system","content":[{"type":"text","text":"SYS PROMPT"}],"source":{"kind":"plugin","plugin":"@deepseek-ai/dsh-system-prompt"}}},"surfaceOp":"append"},
+        {"type":"request/header","seq":3,"time":5,"data":{"header":{"config":{"provider":"fake","model":"fake"},"tools":[{"name":"t1","description":"D1","parameters":{"type":"object"}}]},"reason":"initial"}},
+        {"type":"assistant/attempt","seq":4,"time":5,"data":{"turn":1,"step":1,"stream":[{"type":"text-chunks","time0":5,"index":0,"dt":[],"texts":["hi"]}]}}
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       "lines": [
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-                  "parameters": {
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-                  }
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-              ]
-            },
-            "reason": "initial"
-          }
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+        {"type":"session","version":2,"id":"eeeeeeee-1111-4222-8333-444444444444","createdAt":300,"cwd":"{{CWD}}","isSeeded":false,"delegationDepth":1,"parentSession":"{{SID}}"},
+        {"type":"turn/start","seq":0,"time":5,"data":{"turn":1}},
+        {"type":"step/start","seq":1,"time":6,"data":{"turn":1,"step":1}},
+        {"type":"system/message","seq":2,"time":6,"data":{"turn":1,"step":1,"message":{"id":"aaaaaaaa-aaaa-4aaa-8aaa-aaaaaaaaaaaa","role":"system","content":[{"type":"text","text":"SYS PROMPT\n\nCHILD GUIDANCE"}],"source":{"kind":"plugin","plugin":"@deepseek-ai/dsh-system-prompt"}}},"surfaceOp":"append"},
+        {"type":"request/header","seq":3,"time":6,"data":{"header":{"config":{"provider":"fake","model":"fake"},"tools":[{"name":"child-only","description":"Child D","parameters":{"type":"object"}}]},"reason":"initial"}}
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diff --git a/packages/test-support/session-snapshot/tests/fixtures/suite/shared-pin/behavior.json b/packages/test-support/session-snapshot/tests/fixtures/suite/shared-pin/behavior.json
index c1dcb944d0..2aa58ddbc7 100644
--- a/packages/test-support/session-snapshot/tests/fixtures/suite/shared-pin/behavior.json
+++ b/packages/test-support/session-snapshot/tests/fixtures/suite/shared-pin/behavior.json
@@ -4,140 +4,13 @@
     {
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       "lines": [
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