End-to-end implementation of the design audit's prescription. 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 on a single section.

What lands

Chain of custody (audit findings #2 + #3)

• New CitationBlock primitive renders a GROUNDED IN block above every Mix Chain / Patches / Sonic Element card. Rows are humanized via a new userLabels.ts map (~50 curated entries + humanizeFieldPath fallback so no raw camelCase ever reaches the producer).
• New phase1Picker.ts service walks dotted paths, formats values with unit-aware rules (bpm → "157 BPM", spectralBalance.highs → "+1.1 dB", rt60 → "2.04s", confidence fields → percent, etc.), and computes the worst-confidence band across cited paths.
• The existing ConfidenceBandBadge four-band vocabulary (Solid scaffold / Workable draft / Rough sketch / Unreliable) now appears top-right of every card with citations whose fields have a *Confidence sibling in CONFIDENCE_PAIRS.
• CONFIDENCE_PAIRS exported from phase2Validator.ts so the validator and citation block share one source of truth.
• Retires GroundingBadgeList at the Track Layout site; segmentIndexes ride through a new extraRows prop so arrangement-segment citations land inside the same block as measurement citations.

Recommendations-first IA (audit finding #1)

• MeasurementDashboard moved from the top of the results scroll to the bottom, wrapped in a single section-measurements anchor.
• StickyNav's 9 section-meas-* pills collapse into one trailing Measurements entry. The 9 sub-sections inside the dashboard keep their ids and remain individually scrollable via direct hash links.
• Section order: Style → [v2: Setup / Layout / Routing / Warp] → Audio Observations → Arrangement → Session → Stem Notes → Sonic → Mix Chain → Patches → Measurements.

Applied-recommendations tracker (audit findings #14 + #15)

• New appliedRecommendations.ts service maintains a per-file applied-id set in localStorage, keyed by audio content SHA256 (so renaming the file doesn't reset progress).
• Per-card checkbox affordance on Mix Chain + Patches cards. Section-header chips show N of M applied (suppressed when zero, so first views aren't littered).

Idle value-prop panel (audit finding #5)

• New IdleValuePropPanel replaces the 200px NO SIGNAL DETECTED atmospheric canvas with a producer-readable explanation: "Drop a reference, get a measurement-cited rebuild plan for Live 12." + flow illustration + 3 honest pacing bullets (local measurement ~30s, AI interpretation typically 4–5 min, native devices only).

Header polish (audit #7, #9, #11)

• CPU meter removed — browser-tab CPU is misleading during backend-subprocess analysis.
• Local DSP Engine v1.6.0 eyebrow removed — was the 5th competing identity signal and wrapped to 3 lines at 375px on mobile.
• Dense DAW Lab demoted from accent-chip to a quiet text link.

Engineering vocab cleanup (audit #8 + N3/N4/N5/N8)

• New userLabels.ts map (used everywhere a field path could reach a user).
• Export-button labels: JSON_DATA → Download data, REPORT_MD → Download report.
• FAMILY: NATIVE chip dropped from meta-badge rows (almost-always-the-same noise).
• workflowStage prettified at the view-model layer: SOUND_DESIGN → Sound design, MIX → Mix.
• AI Interpretation gated copy reworded: Developer kill-switch is off… → AI interpretation isn't configured. Set GEMINI_API_KEY on the backend…; status badge INTERPRETATION CONFIG OFF → NOT CONFIGURED, INTERPRETATION USER OFF → OFF.

Patches group structure (audit follow-up)

• New PatchGroupViewModel + buildPatchGroups mirrors Mix Chain's inferProcessingGroup heuristic. Producers see Drum / Bass / Synth / Mid / High-end / Master eyebrows instead of a flat 2-col grid.

Input Source collapse (audit N9)

• Post-analysis, the Input Source panel collapses to a compact summary (filename + M:SS duration + ↺ Analyze new file + Adjust settings). Override resets at the start of each new analysis for predictability.

Progress panel primary readout (audit #6)

• Stage diagnostic message promoted from text-[9px] text-secondary/50 footnote to the visual focus of the progress card.
• Tone-aware fill (progress.tone: running / success / failed) so a failed 100% renders red instead of accent-orange (matches the FAILED stage badge below).

Phase 2 failure mode (audit N1)

• Header subtitle derives from analysisRun.stages.interpretation.status instead of the hardcoded PHASE COMPLETE. No more "PHASE COMPLETE" while INTERPRET is still RUNNING or FAILED.
• StickyNav Phase 2 pills (Sonic / Mix Chain / Patches) render disabled with a hover-reason ("Recommendations not produced this run") instead of silently dropping.
• Retry button gates on error.retryable !== false; non-retryable failures (e.g., GEMINI_NOT_CONFIGURED) surface the error code inline with the full message in the tooltip.

Misc audit follow-ups

• BPM reconciled across the exec card + Core Metrics tile (was 157 vs 156.6) — N2.
• Signal Monitor STANDBY canvas hidden when audio isn't playing, freeing ~160px in the most common state (N7).
• Device Chain → Sections in StickyNav (N10, less ambiguous with Ableton's own "device chain" meaning).
• 🫧 → <AudioWaveform /> Lucide icon for BASS PROCESSING group eyebrow (#2 #13).
• Toggle helper paragraphs in the Input Source panel switched from all-caps mono walls to sans-serif sentence case (fix: chunk Demucs inference and stop boot-time memory spikes #4 revised).

Phase 2 grammar post-process

The prompt instruction added in the prior round didn't take — Gemini still emitted 3rd-person singular forms after "by" in role/reason text ("by recreates", "by absorbs", "by shapes"). New server-side _apply_phase2_grammar_fixes rewrites these to gerunds in-place on:

• mixAndMasterChain[].reason
• abletonRecommendations[].{reason, advancedTip}
• secretSauce.workflowSteps[].{instruction, measurementJustification}

Conservative regex (\bby \w{4,}s\b) + denylist guards against plural-noun false positives ("by samples", "by beats", "by buses" all stay intact).

Test coverage

• UI: 46 test files / 540 tests pass (was 39 / 422 before the audit). Net +118 tests across new services (userLabels, phase1Picker, citationBlock, appliedRecommendations, formatTrackDuration, interpretationSubtitle, workflowStagePrettifier, analysisStatusProgress, idleValuePropPanel, phase2NavReason) plus DOM-level integration tests in analysisResultsUi.test.ts.
• Backend: 16 new unit tests in test_phase2_grammar_fix.py covering _to_gerund, _fix_by_gerund_in_text, and _apply_phase2_grammar_fixes against the actual screenshot corpus. Full ASA backend suite 463 of 463 pass. One pre-existing unrelated failure in tests.test_url_ingest.MimeTypePickerTests.test_octet_stream_triggers_filename_fallback (system MIME registry returns audio/x-flac instead of expected audio/flac) predates this branch.
• Build: npm run build clean. AnalysisResults chunk 247.95 KB / 60.36 KB gzip.

Visual verification

Playwright capture pass against a real 126s track (apps/backend/.runtime/artifacts/0a1e46db-…mp3). Phase 2 returned in 220s on the run. Screenshots in /tmp/asa-shots-audit-final/ confirm every audit surface:

• Header has no CPU meter, no version eyebrow, no header wrap on 375×812.
• GROUNDED IN block visible on every card.
• Confidence pills emerge contextually (SOLID SCAFFOLD · 99% on Acid Bass; WORKABLE DRAFT · 78% on Supersaw Synth).
• 2 OF 8 APPLIED chip after clicking two applied checkboxes; localStorage round-trip survived a page reload.
• Patches grouped under 🥁 DRUM / 🌊 BASS / 🎹 SYNTH / 🧱 MASTER eyebrows.
• Section order reads Style → Sonic → Mix Chain → Patches → Measurements.

The grammar post-process is unit-tested but not yet visually re-verified — the next Phase 2 run against the same fixture will show "by recreating" / "by shaping" / "by absorbing" instead of the 3rd-person singular forms.

Known limitations

• The gerund rule is algorithmic, not dictionary-backed. Verbs requiring English consonant-doubling (control → controlling, submit → submitting, run → running) degrade to "controling" / "submiting". Still better than the original by controls. If observed in real Phase 2 output, drop a hand-mapped exception into the module rather than implement orthographic stress detection.
• One pre-existing test failure on main (tests.test_url_ingest.MimeTypePickerTests.test_octet_stream_triggers_filename_fallback) is unaffected by this PR — audio/x-flac vs audio/flac MIME-registry mismatch from an earlier merged change.

Files

31 files changed, +3,511 / −403.

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