[MM-08] Converge durable-memory and Markdown compatibility contracts

[bug-superman]

MM-08: Converge durable-memory and Markdown compatibility contracts

Parent

#771

Checkpoint

MC-1A Memory correctness

What to build

Unify structured durable-memory states with human-authored Markdown compatibility so legacy content is never silently treated as user-approved structured memory.

Acceptance criteria

• New active entries require confirmation metadata and source refs.
• Legacy Markdown receives an explicit compatibility source and migration state.
• Malformed sections fail safely and remain user recoverable.
• Round-trip projection does not invent approval.
• Compatibility behavior is versioned and documented.

Required tests

• Legacy section matrix
• malformed Markdown
• round trip
• missing metadata
• migration restart/concurrency

Benchmark

Lifecycle compatibility fixtures; no false active promotion is allowed.

Blocked by

• [MM-04] Enforce session, workspace, and privacy gates on memory reads #783 (MM-04)

Rollout and rollback

Keep original Markdown as a read-only source and disable structured migration if conversion fails.

[Astro-Han]

Superseded by #1615 (automatic long-term memory lifecycle, SQLite-based; accepted by maintainers 2026-07-30, PR ① #1770 merged). This MM-08 work item never landed outside draft PR #820 and is replaced by the #1615 design and its LongMemEval/MSC evaluation plan.