OMP session ingestion

Prompt-first procedure: Describe the outcome you want in your agent conversation. The agent should select and load the appropriate AIWG assets, explain material changes, request any needed approval, and report verification evidence. Exact commands and flags appear only in the CLI reference.

OMP is an experimental, separate session provider. Source verification used Oh My Pi 18.1.10 at `5964a0f7649275bcde818f20073193fd032451f2`. The native schema remains version 3 but may start with a mutable 256-byte title slot before the session header. Pi's header-first parser is not used.

Use AIWG to complete this documented outcome: OMP is an experimental, separate session provider. Source verification used Oh My Pi 18.1.10 at 5964a0f7649275bcde818f20073193fd032451f2. The native schema remains version 3 but may start with a mutable 256-byte title slot before the sessio
Have it inspect the current state, explain the plan, ask before material
changes, and report the result with verification evidence.

the provider-home option also authorizes discovery through the shared OMP path resolver, including its environment/profile settings. Without an explicitly authorized home or the omp-root option, OMP shared session roots are not scanned. Discovery filters sessions by the header's workspace and uses native session identity to keep source IDs stable after appends. The manifest still fingerprints exact file contents for batch import verification.

Native messages, model changes, non-transcript model usage, compactions, branch summaries and unknown event types retain event IDs, parent IDs and useful provenance. Header parent-session and previous-file fields retain fork/move provenance under the standard recursive native-field sanitization policy. Tool results, custom content, credential pins, subagent initialization content and unknown payloads are redacted; unknown records retain opaque type/identity and source offsets for authorized inspection.

Checkpoints exclude only a validated fixed-size title slot from the immutable prefix digest. Header/event rewrites, truncation and file replacement still fail with schema drift. Resume rescans through the bounded reader to preserve absolute event sequences and native header identity, then emits events beyond the byte cursor. This trades read throughput for deterministic replay. Title slot contents are presentation metadata; append-only `title_change` records carry title history into the normalized event stream.

Validation: `npx vitest run test/unit/sessions/omp-adapter.test.ts` exercises legacy/current layouts, malformed/missing headers, unknown schema versions, truncated tails, resource/authorization boundaries, Pi isolation, persistent checkpoint replay, title rewrites, appends, rediscovery and batch import. Existing OpenRouter live-test session files were also imported successfully: 5 and 8 events respectively, with zero replay receipts. This verification reads saved sessions and does not perform a model request.