feat(memory): add selective branch pick support

[gouhongshen]

Summary

• add selective branch pick support across git, MCP remote, and REST API
• support key_list, snapshot_range, and retrieve selectors, optional target branch, and fail|skip|accept conflict strategies
• add retrieve.min_score and dry_run preview/output shaping for memory_pick
• add MCP/API/remote e2e coverage for success, validation, conflicts, target branches, retrieve ranking, and dry-run previews

Interface

MCP

Tool: memory_pick

Inputs:

• source: source branch name
• target: optional target branch, defaults to main
• strategy: optional fail | skip | accept, defaults to fail
• selector:
  • {"type":"key_list","keys":["", "..."]}
  • {"type":"snapshot_range","from_snapshot":"snap_a","to_snapshot":"snap_b"}
  • {"type":"retrieve","query":"alpha query","top_k":5,"min_score":0.82} (top_k and min_score only apply to retrieve)
• dry_run (optional preview mode; no database mutation):
  • {"limit":10,"offset":0,"include_content_preview":true,"include_scores":true}
  • limit / offset only shape preview output; they do not change the selected candidate set
  • preview output never includes embeddings

Outputs:

• normal execution returns plain text in content[0].text
• dry_run returns preview JSON rendered in content[0].text, including:
  • result
  • summary
  • page
  • candidates
• v1 intentionally does not add session_id

REST API

POST /v1/branches/:source/pick

Request body:

• target: optional target branch, defaults to main
• strategy: optional fail | skip | accept, defaults to fail
• selector: same shape as MCP
• dry_run: same shape as MCP; when present, returns a structured preview instead of applying changes

Success response:

• normal execution:

{"result":"Picked ..."}

• dry_run preview:

{
  "dry_run": true,
  "result": "Previewed ...",
  "summary": {
    "candidate_count": 2,
    "shown_count": 1,
    "would_apply": 2,
    "would_skip": 0,
    "conflict_count": 0,
    "would_abort": false
  },
  "page": {
    "limit": 1,
    "offset": 0,
    "has_more": true
  },
  "candidates": [
    {
      "memory_id": "019...",
      "content_preview": "alpha branch memory",
      "score": 0.93,
      "status": "would_apply",
      "reason": "new_or_updated_row"
    }
  ]
}

Error mapping:

• 422: validation error
• 404: source/target branch or snapshot not found
• 409: pick conflict when strategy=fail

Testing

• cargo check -p memoria-mcp -p memoria-api
• cargo test -p memoria-mcp --test branch_e2e --no-run
• cargo test -p memoria-api --test api_e2e --no-run
• local runtime pick e2e currently still depends on a ready MatrixOne test DB; on this machine the existing multi-db harness times out before tests start

[Copilot]

Pull request overview

This PR adds a new selective “branch pick” capability that applies a subset of changes from one memory branch into another (defaulting to main), wiring it through MCP tooling, the RemoteClient, and the REST API, with E2E coverage for success and conflict cases.

Changes:

• Introduces memory_pick MCP tool + GitForDataService support for picking by key_list, snapshot_range, or retrieve selectors with conflict strategies.
• Adds REST endpoint POST /v1/branches/:name/pick and RemoteClient forwarding for memory_pick.
• Adds MCP/API/remote E2E tests covering happy paths, validation, and conflict handling.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
memoria/crates/memoria-mcp/tests/branch_e2e.rs	Adds MCP E2E coverage for key_list/snapshot_range/retrieve pick and conflict strategies
memoria/crates/memoria-mcp/src/remote.rs	Forwards memory_pick to the new REST pick endpoint
memoria/crates/memoria-mcp/src/git_tools.rs	Implements memory_pick tool parsing, selection logic, and pick execution
memoria/crates/memoria-git/src/service.rs	Adds MatrixOne DDL helpers for data branch pick (keys + snapshot range)
memoria/crates/memoria-api/tests/api_e2e.rs	Adds REST + remote E2E tests for pick, validation, and conflicts
memoria/crates/memoria-api/src/routes/snapshots.rs	Adds REST handler that calls MCP git_tools pick and maps conflicts to HTTP 409
memoria/crates/memoria-api/src/routes/mcp.rs	Marks memory_pick as dirtying FULL metrics state
memoria/crates/memoria-api/src/models.rs	Adds PickRequest and PickSelector request models
memoria/crates/memoria-api/src/lib.rs	Adds /v1/branches/:name/pick route and metrics dirty-path handling

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[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 2 comments.

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[Copilot]

snapshot_range dry-run candidate query only checks differences between to_snapshot and from_snapshot (s_to vs s_from) and does not filter out rows that are already identical in the target branch. This can inflate candidate_count and mark target_exists rows as conflicts even when picking would be a no-op for that memory_id in the target. Consider also applying the same “pickable vs target” diff predicate (s_to vs target alias) so the preview reflects what would actually change in the target branch.

[Copilot]

map_pick_conflict treats any error whose message contains the substring "conflict" as a pick conflict. Because the SQL statement itself contains "when conflict ...", unrelated failures (notably SQL parser errors on older MatrixOne versions) will be misclassified and returned as MemoriaError::Validation("Conflict: ..."), which the REST layer maps to HTTP 409. Suggest tightening the detection to only match real pick-conflict errors (e.g., by checking specific MatrixOne error codes / a more specific phrase) and letting parser/DDL errors surface as internal errors instead of 409.