feat(obsidian): support observation scopes

[omgbabyweb]

Summary

• add optional named observation_scopes support to the Obsidian retain client
• thread the setting through the shared desktop/headless SyncEngine path
• expose a backward-compatible plugin dropdown and CLI flag
• preserve source tags and omit the request field when unset

This supports banks where trusted ingestion sources need to consolidate observations together while retaining vault/folder/date/frontmatter tags for filtering and provenance. Existing documents are not automatically migrated when the setting changes.

Test plan

• npm run lint
• npm test (113 tests)
• npm run build
• git diff --check

[strix-security]

Strix Security Review

Warning

This pull request has 1 commit after the last Strix review (837c67a). Strix has not reviewed these changes.
Automatic review on push is off for this repository. To review the latest changes, tag @strix-security in a comment, or turn on re-review on push.

No security issues found.

_{Updated for 837c67a.}

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Reviewed by Strix
_{Re-run review · Configure security review settings}

[Sanderhoff-alt]

The field name, the four accepted values and the per-item placement all match MemoryItem.observation_scopes in hindsight-api-slim/hindsight_api/api/http.py:716, and saveSettings() rebuilds the engine so the dropdown takes effect immediately. Two items before merge.

[omgbabyweb]

@Sanderhoff-alt Thanks for the review — both items are addressed in 788bdbf: the requested Prettier reflows are committed, and observationScopes now flows through remembered user and assistant chat retains with focused coverage. Local verification passed TypeScript lint, all 113 tests, production build, Prettier check, and git diff check. Could you please re-review when convenient?

[omgbabyweb]

@strix-security please re-run the security review for the latest commit.