MCPJVM-367: Transitional legacy correlation index backfill for SQLite state-store

[nimbly-dev]

Description

During migration away from shared correlation-index.json, it may be useful to support a temporary compatibility path that imports legacy correlation-oriented index data into the SQLite-backed state-store. This should be treated as transitional migration support only, not as the long-term recovery path.

This story adds transitional legacy backfill/import behavior for correlation-oriented SQLite state-store data where migration support is still needed.

Scope

In scope:

• Support temporary import/backfill from legacy shared correlation-index.json
• Limit legacy import support to correlation-oriented state, and only any partial run linkage needed by that migration path
• Position legacy import as transitional compatibility rather than long-term source-of-truth behavior
• Keep backfill behavior deterministic and fail-closed when legacy data is missing or invalid
• Keep implementation aligned with the existing artifact_management action-plus-shared helper structure

Out of scope:

• Treating legacy shared index data as the long-term recovery path
• Full rebuild of all SQLite state surfaces from legacy index data alone
• New public MCP query/read contracts beyond the migration capability entrypoint
• Performance Suite integration

Expected Tables / Detailed Schema Direction

Primary legacy import target:

correlation_runs

Column	Type	Required from legacy source	Purpose
run_id	TEXT	yes	imported run linkage
project_name	TEXT	yes	owning project
plan_name	TEXT	yes	owning plan linkage
correlation_session_id	TEXT	no	imported session grouping if present
status	TEXT	yes	imported correlation verdict
reason_code	TEXT	yes	imported deterministic reason
key_type	TEXT	yes	imported correlation key type
key_value	TEXT	no	imported resolved key value
window_start_epoch_ms	INTEGER	no	imported window start if present
window_end_epoch_ms	INTEGER	no	imported window end if present
max_window_ms	INTEGER	yes	imported/derived max window
probe_ids_json	TEXT	yes	imported probe id array summary
generated_at_epoch_ms	INTEGER	no	imported sortable timestamp

Optional partial linkage target only when needed:

suite_runs

Column	Type	Required from legacy source	Purpose
run_id	TEXT	yes	linkage only
project_name	TEXT	yes	linkage only
plan_name	TEXT	yes	linkage only
status	TEXT	no	partial inferred status if defensible
generated_at_epoch_ms	INTEGER	no	partial timestamp if present

Legacy backfill should not imply honest reconstruction of watcher_runs or external_verifications from correlation-index-only data.

Acceptance Criteria

• SQLite-backed state-store supports transitional legacy correlation-index import where needed for migration
• Legacy import scope is explicitly limited and does not overstate coverage for watcher or external verification state
• Legacy backfill is positioned as temporary compatibility support rather than long-term recovery behavior
• Backfill fails closed when required deterministic legacy data is missing or invalid
• The implementation remains aligned with the existing artifact_management action-plus-shared helper structure

Implementation Notes

• Treat this as a migration bridge with removal potential in a later release rather than a permanent capability.
• Avoid expanding legacy import semantics to state surfaces that cannot be reconstructed honestly from legacy correlation index data.

Testing

• UT for legacy index parsing and backfill mapping behavior
• UT for fail-closed handling on malformed or incomplete legacy index data
• IT for transitional backfill into an empty SQLite state-store
• IT for deterministic skip/insert behavior on repeated backfill runs