Merge remote-tracking branch 'origin/master' into codex/agent-session-jsonl-location

# Conflicts:
#	docs/capability-seams.md
#	packages/cordis/tool-cordis/src/api-catalog.ts

docs/core-data-structures/core.md

@@ -19,7 +19,7 @@ Everything else is documented on a **sub-page**, not here. The rule that draws t
 | [scope.md](scope.md) | scoped registration identity, dispatch carriers, and the owned `Scope` context |
 | [session.md](session.md) | the full `SessionEventMap` variant catalog, `TurnTrigger`/`TurnEndReason`, `deriveMessages()`, the turn-enclosure invariant |
 | [persistence.md](persistence.md) | the durability seam: `SessionPersistence`, JSONL + SQLite backends, `session/flush`, crash recovery, `SessionHeader` |
-| [session-query.md](session-query.md) | logical session/event records and bounded exact-event reads |
+| [session-query.md](session-query.md) | logical records, bounded exact-event reads, and relationship traces |
 | [system-prompt.md](system-prompt.md) | per-assembly context, tool-provider results, prompt sections, and cooperative assembly |
 | [tools.md](tools.md) | `ToolDefinition` full fields, the schema DSL, `ToolExecution`/`ToolResult`, tool-presentation UI types, and the guarded execution pipeline |
 | [user-interaction.md](user-interaction.md) | the UI-backed human question/answer seam: `AskUserQuestionRequest`, answer/options vocabulary, provider API, error taxonomy |

docs/core-data-structures/session-query.md

@@ -1,6 +1,6 @@
 # Session Query
 
-Exact reads over the live-preferred logical session corpus. The [package contract](../../packages/session-query/session-query) owns source precedence, dynamic optional persistence, cloning, surface classification, bounded windows, and typed failures. Full-text search is a separate proposed SQLite phase.
+Exact reads and relationship traces over the live-preferred logical session corpus. The [package contract](../../packages/session-query/session-query) owns source precedence, dynamic optional persistence, cloning, surface classification, bounded windows, tracing validation, and typed failures. Full-text search is a separate proposed SQLite package.
 
 Source: [`packages/session-query/session-query/src/types.ts`](../../packages/session-query/session-query/src/types.ts)
 
@@ -30,6 +30,34 @@ export interface SessionEventRecord {
 }
 ```
 
+## Session lineage
+
+`SessionLineageTrace` carries known parents in immediate-to-outward order and a forest of recursively nested direct descendants. The completeness discriminant makes a known root and a missing parent mutually exclusive.
+
+```ts type-equiv
+export interface SessionLineageNode {
+  session: SessionRecord
+  descendants: SessionLineageNode[]
+}
+```
+
+```ts type-equiv
+export type SessionLineageTrace = {
+  target: SessionRecord
+  ancestors: SessionRecord[]
+  descendants: SessionLineageNode[]
+} & (
+  | {
+    complete: true
+    root: SessionRecord
+  }
+  | {
+    complete: false
+    unresolvedParentId: SessionId
+  }
+)
+```
+
 ## Bounded event reads
 
 The request addresses one raw seq and optional neighboring counts. The result carries a `SessionHeader` rather than availability flags so a known live target can remain independent of persistence health.
@@ -53,6 +81,28 @@ export interface SessionEventWindow {
 }
 ```
 
+## Event relationships
+
+Event traces distinguish positional surface replacement from logged provenance. Every seq list contains direct links except `replacementChain`, which follows immediate replacers from the target to the final positional replacement.
+
+```ts type-equiv
+export interface SessionEventTraceRequest {
+  sessionId: SessionId
+  seq: number
+}
+```
+
+```ts type-equiv
+export interface SessionEventTrace {
+  target: SessionEventRecord
+  replacedBy?: number
+  replacementChain: number[]
+  replacedEventSeqs: number[]
+  sourceEventSeqs: number[]
+  derivedEventSeqs: number[]
+}
+```
+
 ## Errors
 
 The closed code union distinguishes request validation, missing targets, malformed surface logs, optional-backend failure, and contradictory source metadata.
@@ -61,6 +111,7 @@ The closed code union distinguishes request validation, missing targets, malform
 export type SessionQueryErrorCode =
   | 'SESSION_QUERY_EVENT_NOT_FOUND'
   | 'SESSION_QUERY_INVALID_CONFIG'
+  | 'SESSION_QUERY_INVALID_LINEAGE'
   | 'SESSION_QUERY_INVALID_SURFACE'
   | 'SESSION_QUERY_INVALID_WINDOW'
   | 'SESSION_QUERY_PERSISTENCE_FAILED'