…rammar post-process

Implements the design audit's prescription end-to-end (findings #1–#15 + N1/N2/N7/N9/N10
+ follow-ups). The product's chain-of-custody promise — every Phase 2 recommendation
traces back to the Phase 1 measurement that justifies it — is now visually first-class
on every card, not a 9px monospace footnote.

What ships:

* Chain-of-custody (findings #2 + #3). New CitationBlock primitive renders a structured
  "GROUNDED IN" block above every Mix Chain / Patches / Sonic Element card with
  humanized labels (FIELD_LABELS map, ~50 entries + humanizeFieldPath fallback) and a
  ConfidenceBandBadge pill computed from the worst confidence among cited fields.
  Also retires GroundingBadgeList at the Track Layout site; segmentIndexes ride
  through a new extraRows prop.

* Recommendations-first IA (#1). MeasurementDashboard moved to the bottom of the
  results scroll; StickyNav's 9 measurement pills collapse to one trailing
  "Measurements" entry. Producers hit Style → Sonic → Mix Chain → Patches → Session
  before the measurement evidence.

* Header polish (#7, #9, #11). CPU meter removed (browser-tab CPU is misleading
  during backend analysis), "Local DSP Engine v1.6.0" eyebrow removed (resolves
  mobile 3-line wrap), Dense DAW Lab demoted from accent chip to quiet text link.

* Engineering vocab cleanup (#8 + N3/N4/N5/N8). New userLabels.ts service translates
  field paths to producer-readable labels at every render. Button labels renamed
  (Download data / Download report). FAMILY: NATIVE chip dropped from meta-badge rows.
  workflowStage prettified at the view-model layer ("Sound design" not "SOUND_DESIGN").
  AI Interpretation gated copy reworded ("AI interpretation isn't configured…" not
  "Developer kill-switch is off").

* Applied-recommendations tracker (#14 + #15). Per-card checkbox affordance + section-
  header "N of M applied" chip + localStorage persistence keyed by audio content
  SHA256. Producer can rename their file without losing their progress.

* Idle value-prop panel (#5). Replaces the 200px "NO SIGNAL DETECTED" canvas with
  a producer-readable explanation of what ASA does, with honest pacing copy
  (4–5 min Phase 2 wait, not 2–5 min).

* Patches group structure. Mirrors Mix Chain's emoji-eyebrow grouping (Drums / Bass /
  Synth / Master) so producers can jump to the bass patch without scanning 8 cards.

* Input Source collapse (N9). Post-analysis, the Input Source panel collapses to a
  compact summary with filename + duration + "Analyze new file" + "Adjust settings".
  Frees the top of the page for the results the user came for.

* AnalysisStatusPanel primary readout (#6). Stage diagnostic message promoted from
  9px footnote to the visual focus of the progress card. Pre-existing tone-aware
  fill (running / success / failed) preserved.

* Phase 2 failure mode (N1). Header subtitle derives from interpretation stage status
  (no more "PHASE COMPLETE" while INTERPRET still RUNNING/FAILED). StickyNav Phase 2
  pills render disabled with hover-reason when sections didn't populate. Retry button
  gated on error.retryable; non-retryable failures surface the error code inline.

* Misc audit follow-ups: BPM reconciled across exec card + Core Metrics tile (N2);
  Signal Monitor STANDBY canvas hidden when audio isn't playing, freeing ~160px (N7);
  StickyNav label "Device Chain" → "Sections" (N10, less ambiguous with Ableton's own
  effects-routing meaning); BASS group icon swapped from 🫧 → Lucide AudioWaveform
  (#13); toggle helper paragraphs switched from all-caps mono walls to sans-serif
  sentence case (#4 revised).

* Phase 2 grammar post-process (audit final round). The prompt instruction added
  earlier didn't take — Gemini still emits "by recreates / by absorbs / by shapes"
  3rd-person singular forms after "by" in role/reason text. Server-side
  _apply_phase2_grammar_fixes rewrites these to gerunds in-place on
  mixAndMasterChain[].reason, abletonRecommendations[].{reason,advancedTip}, and
  secretSauce.workflowSteps[].{instruction,measurementJustification}. Conservative
  regex (\bby \w{4,}s\b) + denylist guards against plural-noun false positives.

Test coverage:

* UI: 46 test files / 540 tests pass (was 39/422 before the audit). New service tests:
  userLabels (21), phase1Picker (25), citationBlock (12), appliedRecommendations (16),
  formatTrackDuration (12), interpretationSubtitle (10), workflowStagePrettifier (8),
  analysisStatusProgress (6), idleValuePropPanel + phase2NavReason. New DOM tests in
  analysisResultsUi.test.ts cover Track Layout citation, applied-checkbox flow, mix-
  chain citation rendering.

* Backend: 16 new unit tests in test_phase2_grammar_fix.py cover _to_gerund,
  _fix_by_gerund_in_text, _apply_phase2_grammar_fixes including the actual
  screenshot corpus (recreates → recreating, shapes → shaping, matches → matching,
  etc.). Full suite: 463 of 463 ASA tests pass; 1 unrelated pre-existing failure
  in tests.test_url_ingest predates this branch.

Visual verification: Playwright capture pass against a real 126s track confirmed
every surface (15 screenshots in /tmp/asa-shots-audit-final/). Phase 2 returned in
220s; localStorage round-trip verified on applied-checkbox toggles.

Documented limitations:

* The gerund rule is algorithmic — verbs requiring consonant doubling (control →
  controlling, submit → submitting) degrade to "controling" / "submiting". Still
  better than "by controls". Drop a hand-mapped exception into the module if
  observed in real output.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>