The hierarchical 3-column drill-down was hard to scan and forced a stateful
walk per tag. Replaced with a flat, columns-as-tactics matrix that mirrors
attack.mitre.org/# — every cell is a one-click select target, with inline
sub-technique expand via a `+N` chevron.
- New endpoint GET /api/v1/mitre/matrix returns the full grid (tactics →
techniques → sub-techniques nested) in a single ~55 KB response, so the
SPA renders the whole matrix without firing 15 parallel queries. Two
pytest tests added (nested structure + auth required).
- MitreTagPicker.tsx rewritten as a horizontal-scrolling matrix:
- Click a tactic header → select the tactic (cyan filled).
- Click a technique cell → select the technique (orange filled).
- Click the `+N` chevron → expand sub-techniques inline within the column.
- Click a sub-technique → select (purple filled).
- Single Filter field matches on external_id or name across all kinds.
- Selection chips at the top, clickable to remove.
- `aria-pressed` on every clickable cell for screen readers and Playwright.
- e2e test updated to walk the new flow (click cell → assert aria-pressed,
expand chevron, click sub, verify chip + JSON preview, filter to T1078).
- Spec §F2 + §F12 + todo.md M4 entry updated to make the matrix layout the
canonical UI for MITRE tagging (so future spec-reviewer passes accept it).
- testing-m4.md walkthrough rewritten for the flat picker.
DoD post-refactor: make test-api → 53 passed (was 51), make e2e → 34 passed.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
- backend/tests/test_mitre.py: 12 integration tests using a hand-crafted
minimal STIX bundle (no network in tests). Covers parser
(revoked/deprecated skip, sub-technique parent linkage), seed idempotence,
persisted settings, checksum mismatch path, all four read endpoints, perm
enforcement on /mitre/sync, ILIKE search.
- e2e/tests/m4-mitre.spec.ts: 6 Playwright tests against the live stack.
beforeAll calls POST /mitre/sync once (real bundle, ~50 MB, ~1.1 s) then
the suite validates tactics ≥14, T1003 has ≥5 sub-techniques, the picker
walks tactic→technique→subtechnique with chip multi-select, and non-admin
sees /mitre but no Sync card.
- tasks/testing-m4.md: manual + automated checklist, air-gapped operator
notes, volume-permission caveat for pre-existing root-owned volumes.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
