feat(memory): preserve corroborating episode evidence

STRUCTURE.md

@@ -173,7 +173,7 @@ Unless specified otherwise, TypeScript paths are relative to `packages/plugin/`
 - `src/hooks/magic-context/compaction-off-transition.ts`: Reconcile per-session compaction mode records and process off/on mode transitions.
 - `src/hooks/magic-context/child-session-spawn.ts`: Enforce child session spawn choke point with schema fence validation.
 - `src/shared/escalation-bands.ts`: Derive context limit escalation bands and threshold bounds.
-- `src/features/magic-context/migrations.ts`: Versioned schema migrations v1–v78 (`LATEST_SUPPORTED_VERSION` in `storage-db.ts` must track the highest; `schema-version-fence.test.ts` asserts they stay in lockstep).
+- `src/features/magic-context/migrations.ts`: Versioned schema migrations v1–v79 (`LATEST_SUPPORTED_VERSION` in `storage-db.ts` must track the highest; `schema-version-fence.test.ts` asserts they stay in lockstep). v79 adds content-bound memory episode evidence.
 - `src/features/magic-context/message-index.ts`: FTS-backed raw-message index for `ctx_search`.
 - `src/features/magic-context/search.ts`: Unified retrieval over memories, raw messages, git commits, and session/smart notes.
 - `src/features/magic-context/session-project-storage.ts`: Persist session-to-project bindings and repair mis-scoped compartment chunk embeddings.
@@ -200,7 +200,7 @@ Unless specified otherwise, TypeScript paths are relative to `packages/plugin/`
 - `crates/mc-module/src/session_resolver.rs`: Resolves incoming MCP facade requests to their backing project and session.
 - `crates/mc-module/src/lib.rs`: Route subc client requests, implement MCP tool facade routing (supporting `agent_drops.append` queue drops with server-side range parsing and command-id idempotency checks), serve prompt guidance, manage durable pass tracing for transform passes, orchestrate `session.status`, `session.wrapup`, and `session.delete` operations (utilizing structured status fields, machine-readable dispositions, and process-local per-session latches under a `MAX_WRAPUP_REQUEST_BUDGET` deadline, with `session.delete` atomically removing session-owned rows from SQLite tables), track transform dispatch health metrics and heartbeat reporting, manage LRU-bounded `InFlight` snapshot caching, and coordinate bootstrap state imports using `StateImportCoordinator`.
 - `crates/mc-module/src/historian_producer.rs`: Implement the Rust subc historian producer client using the wire v2 protocol with `OpenedRoute` targeting (channel and epoch routing).
-- `crates/mc-store/src/lib.rs`: Define durable session schemas and migrations (including the `mc_reduce_command_ledger` table in migration 16 for idempotency, `mc_project_mural_artifacts` in migration 49 for project mural artifacts, and `raw_messages_deflate` in migration 50 on `mc_chunk_transcripts` for durable `ctx_expand` recovery), handle metadata, and run CAS transitions.
+- `crates/mc-store/src/lib.rs`: Define durable session schemas and migrations (including the `mc_reduce_command_ledger` table in migration 16 for idempotency, `mc_project_mural_artifacts` in migration 49 for project mural artifacts, `raw_messages_deflate` in migration 50 on `mc_chunk_transcripts` for durable `ctx_expand` recovery, and content-bound memory evidence in migration 51), handle metadata, and run CAS transitions.
 - `crates/mc-module/src/codec/`: Decode harness-specific JSON messages (OpenCode, Pi) into canonical `CkIngressMessage` values and encode them back using harness model codecs.
 - `crates/mc-module/src/caveman.rs`: Age-tier caveman text compression ported to Rust.
 - `crates/mc-module/src/divergence.rs`: Per-pass transform output divergence tracking and attribution.

crates/mc-module/src/lib.rs

@@ -66,7 +66,8 @@ use mc_store::TagNumberRow;
 use mc_store::{
     canonical_root, validate_state_import_compartments, AuthoritySeedRow, DeferredExecuteState,
     FacadeMutationOutcome, HistorianPhase, InsertMemoryInput, MappingUpdate, McStore, McStoreError,
-    ModuleDropSeedRow, ModuleMemoryMutationRow, ModuleMemoryRow, ModuleStateSyncError,
+    ModuleDropSeedRow, ModuleMemoryEvidenceRow, ModuleMemoryMutationRow, ModuleMemoryRow,
+    ModuleStateSyncError,
     ModuleStateSyncRequest, ModuleStripSeedRow, ModuleWorkspaceMemberRow, ModuleWorkspaceRow,
     NoteCasOutcome, NoteEvaluationInput, NoteInput, NoteNudgeAnchorSeed, NoteWriteInput,
     PendingAgentDrop, PendingAgentDropSeedRow, PendingCompactionMarkerState,
@@ -1697,6 +1698,18 @@ struct ModuleMemoryWire {
     mural_cue_at: Option<i64>,
     #[serde(default)]
     mural_cue_rejection_count: i64,
+    #[serde(default)]
+    evidence: Vec<ModuleMemoryEvidenceWire>,
+}
+
+#[derive(Debug, Clone, Deserialize)]
+struct ModuleMemoryEvidenceWire {
+    content_hash: String,
+    source_session_id: String,
+    #[serde(default)]
+    source_message_id: Option<String>,
+    source_type: String,
+    observed_at: i64,
 }
 
 #[derive(Debug, Clone, Deserialize)]
@@ -1804,6 +1817,17 @@ impl ModuleMemoryWire {
             mural_cue_hash: self.mural_cue_hash,
             mural_cue_at: self.mural_cue_at,
             mural_cue_rejection_count: self.mural_cue_rejection_count,
+            evidence: self
+                .evidence
+                .into_iter()
+                .map(|row| ModuleMemoryEvidenceRow {
+                    content_hash: row.content_hash,
+                    source_session_id: row.source_session_id,
+                    source_message_id: row.source_message_id,
+                    source_type: row.source_type,
+                    observed_at: row.observed_at,
+                })
+                .collect(),
         }
     }
 }
@@ -10423,6 +10447,7 @@ impl McHandler {
                                     category,
                                     content,
                                     source_session_id: Some(conversation_key),
+                                    source_message_id: None,
                                     source_type: Some("agent"),
                                     importance: Some(50),
                                     expires_at: None,
@@ -10464,6 +10489,24 @@ impl McHandler {
                                 .update_memory_content(memory_project, id, content, now_ms())
                                 .map_err(|error| error.to_string())?
                                 .ok_or_else(|| format!("memory {id} was not found"))?;
+                            tx.record_memory_evidence(
+                                memory.id,
+                                InsertMemoryInput {
+                                    project_path: memory_project,
+                                    route_project_root: Some(
+                                        facade_scope.route_project_root.as_str(),
+                                    ),
+                                    category: &memory.category,
+                                    content,
+                                    source_session_id: Some(conversation_key),
+                                    source_message_id: None,
+                                    source_type: Some("agent"),
+                                    importance: memory.importance,
+                                    expires_at: memory.expires_at,
+                                    metadata_json: memory.metadata_json.as_deref(),
+                                    now_ms: now_ms(),
+                                },
+                            )?;
                             facade_text_response(
                                 format!(
                                     "Updated memory [ID: {}] in {}.",
@@ -10545,6 +10588,24 @@ impl McHandler {
                                 )
                                 .map_err(|error| error.to_string())?
                                 .ok_or_else(|| format!("memory {target_id} was not found"))?;
+                            tx.record_memory_evidence(
+                                memory.id,
+                                InsertMemoryInput {
+                                    project_path: memory_project,
+                                    route_project_root: Some(
+                                        facade_scope.route_project_root.as_str(),
+                                    ),
+                                    category: &memory.category,
+                                    content,
+                                    source_session_id: Some(conversation_key),
+                                    source_message_id: None,
+                                    source_type: Some("agent"),
+                                    importance: memory.importance,
+                                    expires_at: memory.expires_at,
+                                    metadata_json: memory.metadata_json.as_deref(),
+                                    now_ms: now_ms(),
+                                },
+                            )?;
                             facade_text_response(
                                 format!(
                                     "Merged memories into [ID: {}] in {}; superseded [{}].",
@@ -16700,6 +16761,7 @@ mod tests {
                 category,
                 content,
                 source_session_id: Some(project),
+                source_message_id: None,
                 source_type: Some("test"),
                 importance: Some(50),
                 expires_at: None,
@@ -22330,6 +22392,7 @@ mod tests {
             .any(|memory| memory.content == "second shared fact"));
         let first = store.get_memory_full(project_rows[0].id).unwrap().unwrap();
         assert_eq!(first.source_session_id.as_deref(), Some(key_a));
+        assert_eq!(first.source_type.as_deref(), Some("agent"));
         assert!(store
             .load_active_memories(key_a, now_ms())
             .unwrap()

crates/mc-module/src/m0_compose.rs

@@ -652,6 +652,7 @@ mod tests {
                 category: "CONSTRAINTS",
                 content: "must stay hidden",
                 source_session_id: None,
+                source_message_id: None,
                 source_type: Some("agent"),
                 importance: Some(50),
                 expires_at: None,

crates/mc-module/src/m1_compose.rs

@@ -569,6 +569,7 @@ mod tests {
             category,
             content,
             source_session_id: None,
+            source_message_id: None,
             source_type: Some("tool"),
             importance: Some(70),
             expires_at: None,

crates/mc-module/src/memory_tool.rs

@@ -549,6 +549,7 @@ mod tests {
             category,
             content,
             source_session_id: None,
+            source_message_id: None,
             source_type: Some("tool"),
             importance: Some(50),
             expires_at: None,

crates/mc-module/src/transform.rs

@@ -13984,6 +13984,7 @@ pub(crate) mod tests {
             category,
             content,
             source_session_id: None,
+            source_message_id: None,
             source_type: Some("tool"),
             importance: Some(70),
             expires_at: None,