Epoch reviewer Phase 1: interactive rejection + live ERP + apply/save

[jdpigeon]

What & why

Phase 1 of the Interactive Epoch Review UI (docs/epoch-review-ui-plan.md) — this is the phase that makes it a fully working, interactive epoch cleaner and delivers the onboarding payoff: click bad epochs and watch the ERP clean up live.

Builds on Phase 0 (static reviewer, PR #223) and the write-back bridge (PR #222). Locked decisions implemented: OQ1 = Canvas 2D, OQ2 = extend dataKey / no RPC, OQ6 = live ERP computed client-side.

What you can now do (QA flow)

1. Clean screen → Load Dataset → epoch traces render (Phase 0).
2. Click an epoch column → it greys out (marked for rejection); click again to restore. Prev/Next to page through all epochs; amplitude ＋/－ to scale.
3. Live ERP pane re-averages the non-rejected epochs per condition instantly on every click — the waveform visibly cleans up. Channel selectable via dropdown.
4. Clean Data → drops the marked epochs in Python (bit-identical to MNE), saves -cleaned-epo.fif to disk (via the PR Fix broken Clean→Analyze round-trip: persist cleaned epochs to host disk #222 bridge), refreshes stats.
5. Analyze → the cleaned file is picked up; ERP/topo/PSD reflect the cleaned epochs.

How it works

click epoch → onToggleEpoch(absoluteIndex) → CleanComponent.rejectedEpochs (Set)
   → LiveErpPane: meanTrace() over NON-rejected epochs, per condition, redraw   ← client-side, 0 worker calls
Clean Data → CleanEpochs({dropIndices, badChannels:[]})
   → cleanEpochsEpic: apply_rejection(raw_epochs, [...], []);  ← trailing ';' suppresses the Epochs PyProxy
   → saveEpochs (write-back, PR #222) → requestEpochArrays + GetEpochsInfo (FIFO)

Changes

• utils.py — apply_rejection(epochs, drop_indices, bad_channels) (epochs.drop + info['bads']), native-tested bit-identical to a manual MNE drop/bads.
• epochArrays.ts — pure meanTrace(buffer, meta, epochIndices, channel) ERP primitive (unit-tested vs manual mean, empty → zeros).
• EpochReviewer.tsx — now interactive/controlled: click-to-reject (grey wash + ✕), offset-aware navigation, amplitude gain (clamped, no lane bleed).
• LiveErpPane.tsx (new) — per-condition live ERP over non-rejected epochs; redraws on every toggle; NaN-guarded empty state.
• worker/action/epic — applyRejection() (trailing ;), CleanEpochs({dropIndices, badChannels}), cleanEpochsEpic rewritten to apply → save → refresh.

Out of scope (later phases)

Bad-channel flagging UI (Phase 2 — apply_rejection takes the param, UI wires []), auto-flag from drop_log (Phase 2), onboarding/guided mode (Phase 3).

Verification

• npm run typecheck — 0 errors
• eslint — 0 errors (2 benign warnings, incl. one pre-existing sidebar warning)
• npx vitest run — 44/44 (new: meanTrace, EpochReviewer overlay-click → onToggleEpoch)
• native pytest tests/analysis/ — 14/14 (4 new apply_rejection bit-identical/drop-count/no-op/identity)
• npm run build — green
• Independent adversarial review traced the interaction→apply path (correct absolute-index mapping across navigation — no wrong-epoch-drop bug), confirmed zero-worker live ERP, bit-identical apply, index-shift safety, and no scope drift. Verdict: PASS.

Stacked on epoch-reviewer-phase0 (PR #223). 🤖 Generated with Claude Code