Summary

Introduces the continuity model Lossless Claw needs to map onto OpenClaw's database-first runtime without treating every runtime sessionId change as a brand-new logical conversation.

This PR adds explicit:

• familyKey
• segmentKey
• runtime sessionId

to LCM conversation identity.

That lets LCM represent:

• one logical family across multiple runtime sessions
• one logical segment within that family until a real lifecycle split happens
• explicit new segments for /reset, idle, and daily lifecycle events

This is the implementation slice for #642, stacked on top of the SQLite frontier work in #646.

Why this is better

OpenClaw's newer runtime semantics separate:

• stable logical ownership
• lifecycle-driven session replacement
• raw runtime sessionId churn

LCM's older model was effectively:

• stable sessionKey when present
• otherwise raw sessionId

That is too weak once the canonical source is a multi-entity SQLite runtime.

This PR gives LCM a continuity model that matches the architecture we actually want:

• stable family continuity
• explicit segment splits
• runtime sessionId as an operational identity, not the whole story

Architecture

flowchart LR
    A["familyKey"] --> B["segmentKey"]
    B --> C["runtime sessionId"]
    A --> D["logical conversation family"]
    B --> E["current active segment"]
    C --> F["current runtime owner"]

Lifecycle mapping in this PR:

• same sessionKey, new runtime sessionId: same family, same segment
• /reset: same family, new segment
• idle: same family, new segment
• daily: same family, new segment

What changed

Schema and migration

• adds family_key and segment_key to conversations
• backfills older rows forward from legacy session identity
• adds supporting indexes for active family lookup and unique segment identity

ConversationStore continuity rules

• getOrCreateConversation(...) now reasons about family and segment continuity explicitly
• active family reuse updates runtime sessionId in place
• legacy sessionId rows can backfill into keyed family continuity without creating duplicates

Engine lifecycle behavior

• lifecycle replacement now creates fresh segments inside an existing family instead of creating unrelated identity islands
• runtime logs include family and segment information so later slices can reason about continuity explicitly

Non-goals

This PR does not:

• solve bootstrap message_parts fidelity from #643
• remap maintenance / rotate / GC behavior from #644
• redesign the SQLite frontier from #645

Validation

cd /Volumes/LEXAR/repos/lossless-claw-642-identity
pnpm test \
  test/message-identity.test.ts \
  test/engine.test.ts \
  test/regression-2026-03-17.test.ts \
  test/lcm-tools.test.ts

Observed locally:

• 4 files passed
• 254 tests passed

Stack placement

This is the continuity-model slice for LCM vNext.

Related stack:

• umbrella: Martian-Engineering/lossless-claw#641
• frontier base: Martian-Engineering/lossless-claw#646
• tracked issue: Martian-Engineering/lossless-claw#642
• later fidelity slice: Martian-Engineering/lossless-claw#643
• later maintenance slice: Martian-Engineering/lossless-claw#644
• upstream refactor context: openclaw/openclaw#78595

Issue

Refs Martian-Engineering/lossless-claw#642.