docs: cut the comments that were not earning their place

I wrote 731 comment lines on this branch against 4,530 lines of code — 14%,
where the rest of the repo runs at 1.8%. CLAUDE.md asks for code that reads
like its surroundings, and this did not.

Removed by genre rather than by taste:

- restating the code, e.g. "JS getUTCDay() numbering: Sunday = 0" above the
  map that literally shows it, and a docblock on startOfWeek explaining that
  it returns the start of the week;
- narrating history — "this used to rebuild the whole map", "left the bar
  recording forever" — which the commit message and git blame already carry;
- saying the same thing in several places: the "cannot record is not a
  denied microphone" reason appeared three times in one file, and the
  "aborting stops a per-minute metered call" reason across three files. Each
  now lives once, where the behaviour it explains lives;
- defending decisions nobody would question, like why toLatinDigits is its
  own module;
- over-explaining defensive branches, three separate comments to distinguish
  null from missing-kind from unrecognised-kind.

What stays is what the code cannot say: the patient-right convention in
toFdi, whose failure mode is a valid code for the wrong tooth; the
"this"-vs-"next" week anchoring; StrictMode re-arming mountedRef; Safari
accepting no mimeType hint; and the invariants whose violation already cost
a bug — the body parser's middleware ordering and the dispatch panel's
auto-fill rules.

Comments only. The diff contains no non-comment line.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

frontend/src/components/treatment/voiceReviewRows.ts

@@ -19,14 +19,9 @@ export function voiceRowAvailability(result: VoiceExtractionResult) {
 }
 
 /**
- * Which rows start ticked.
- *
- * Everything available ticks itself, with two deliberate exceptions:
- *
- * - **lab, when the name only approximately matched.** Shipping a case to a lab is the one
- *   extracted value whose error leaves the building, so it always requires a deliberate tick.
- * - **prosthesis, when the map is incomplete.** A prosthesis detail with an untyped tooth
- *   cannot ship at all, so applying it would just move the failure to dispatch.
+ * Everything available ticks itself, with two exceptions: an inexactly-matched lab, because
+ * it is the one extracted value whose error leaves the building; and an incomplete
+ * prosthesis map, which cannot ship at all and would just move the failure to dispatch.
  */
 export function initialVoiceSelection(result: VoiceExtractionResult): VoiceApplySelection {
   const available = voiceRowAvailability(result);
@@ -41,11 +36,8 @@ export function initialVoiceSelection(result: VoiceExtractionResult): VoiceApply
 }
 
 /**
- * How many rows will actually be applied — drives the confirm button's label.
- *
- * Intersected with availability rather than counting ticks: a row can be ticked and then
- * lose its content (the last candidate tooth un-picked), and "Apply 1 item" that applies
- * nothing is worse than a wrong number.
+ * Intersected with availability rather than counting ticks: a row can be ticked and then lose
+ * its content, and "Apply 1 item" that applies nothing is worse than a wrong number.
  */
 export function countSelected(
   selection: VoiceApplySelection,
@@ -66,16 +58,10 @@ function recheckProsthesis(
 }
 
 /**
- * Fold the clinician's candidate picks into the extracted result.
+ * Fold the candidate picks into the result, so nothing downstream has to know chips exist.
  *
- * Everything downstream reads a `VoiceExtractionResult` — row availability, the mini
- * chart, the prosthesis warning, `applyVoiceResult` — so resolving the picks into one here
- * means none of them has to know the chips exist.
- *
- * Union rather than toggle, for two reasons: a candidate can coincidentally be a tooth the
- * recording already produced ("۱۲ و دو"), where tapping it must not deselect that tooth;
- * and `groupsFromFlatTeeth` keeps the bridges intact while giving every remaining tooth a
- * single group, so no tooth can be lost on the way through.
+ * Union rather than toggle: a candidate can coincidentally be a tooth the recording already
+ * produced ("۱۲ و دو"), and tapping it must not deselect that one.
  */
 export function withChosenTeeth(
   result: VoiceExtractionResult,
@@ -103,12 +89,7 @@ export function connectedTeethFromResult(result: VoiceExtractionResult): Set<Fdi
   return connected;
 }
 
-/**
- * Whether the sheet has anything worth showing.
- *
- * A recording that produced nothing usable should say so plainly rather than present an
- * empty form of checkboxes.
- */
+/** A recording that produced nothing should say so, not show an empty form of checkboxes. */
 export function hasAnythingToApply(result: VoiceExtractionResult): boolean {
   return Object.values(voiceRowAvailability(result)).some(Boolean);
 }

frontend/src/components/ui/treatment/TreatmentDetailsEditor.tsx

@@ -338,17 +338,12 @@ function NotesField({
 /**
  * "Add detail", split into two segments with the microphone at the logical end.
  *
- * Built like the detail chip's trash affordance in this same file — an
- * `inline-flex items-stretch overflow-hidden rounded` wrapper holding two raw `<button>`s
- * divided by `border-s` — rather than two shared `Button`s, which each hardcode their own
- * rounding and would fight a segmented control.
+ * Built like the detail chip's trash affordance in this same file — a wrapper holding two
+ * raw `<button>`s divided by `border-s` — rather than two shared `Button`s, which hardcode
+ * their own rounding and would fight a segmented control. `border-s` puts the microphone
+ * visually right in en/nl and left in fa, on the same side as the chip's trash in both.
  *
- * `border-s` puts the microphone at the *logical* end: visually right in en/nl, visually
- * left in fa, on the same side as the chip's trash in both directions.
- *
- * The two halves share a wrapper and nothing else. Add keeps its exact existing
- * behaviour; the microphone is an independent action that creates nothing until the
- * clinician confirms.
+ * Add keeps its exact existing behaviour; the microphone is an independent action.
  */
 function AddDetailWithVoice({
   addLabel,

frontend/src/components/ui/treatment/TreatmentWorkspace.tsx

@@ -2000,8 +2000,7 @@ export function TreatmentWorkspace({
 
       const nextDetails = [...detailsRef.current, detail];
       setDetails(nextDetails);
-      // persistDraft reads detailsRef, and setDetails has not rendered yet. The codebase
-      // already writes this ref imperatively after a save for the same reason.
+      // persistDraft reads detailsRef, and setDetails has not rendered yet.
       detailsRef.current = nextDetails;
       setActiveDetailId(detail.clientId);
       setEntryStep('treatment');
@@ -2045,19 +2044,16 @@ export function TreatmentWorkspace({
         const updatedLabCases = [...labCaseDrafts, draft];
         setLabCaseDrafts(updatedLabCases);
 
-        // Every other path that creates a lab draft persists it immediately, and the
-        // autosave effect only watches `details`. Left in state alone, the destination
-        // lab, the due date and the whole prosthesis map vanish on the next reload —
-        // silently, because the detail itself does survive.
+        // Autosave only watches `details`, so a lab draft left in state alone loses the
+        // lab, the due date and the prosthesis map on reload — silently, because the
+        // detail itself survives.
         void (async () => {
           try {
             const saved = await persistDraft({ force: true });
-            // persistDraft returns a *preview* treatment rather than saving when the
-            // details are not persistable — one blank detail, the kind the workspace opens
-            // with, is enough. A preview's detail id falls back to the client id, so
-            // posting lab cases against it would send the server an id it has never seen
-            // and fail the whole save. Check what came back, not the precondition, so this
-            // holds for every early return persistDraft has.
+            // persistDraft returns a *preview* when the details are not persistable — one
+            // blank detail is enough — and a preview's detail id falls back to the client
+            // id. Check what came back, not the precondition, so this holds for every early
+            // return persistDraft has.
             const savedDetail = saved.details.find((d) => d.clientId === detail.clientId);
             if (!savedDetail?.id || savedDetail.id === detail.clientId) return;
             await persistLabCases(saved, updatedLabCases);

frontend/src/components/ui/treatment/VoiceRecordingBar.tsx

@@ -16,9 +16,9 @@ function formatElapsed(ms: number): string {
 /**
  * Live recording / processing strip.
  *
- * Sits between the header row and the chip strip rather than inside the segmented
- * control: the header is `sm:justify-between`, so growing the button mid-recording would
- * shove the row on every start and every stop.
+ * Sits between the header row and the chip strip rather than inside the segmented control:
+ * the header is `sm:justify-between`, so growing the button mid-recording would shift the
+ * whole row.
  */
 export function VoiceRecordingBar({ voice }: { voice: VoiceCaptureState }) {
   const t = useTranslations('treatment');

frontend/src/components/ui/treatment/VoiceReviewSheet.tsx

@@ -38,9 +38,8 @@ interface VoiceReviewSheetProps {
 /**
  * Confirmation step between the model's output and the form.
  *
- * Modal on desktop, bottom sheet on mobile via ResponsiveDialog — deliberately an overlay
- * and not a route, because navigating would unmount TreatmentWorkspace and destroy the
- * in-progress draft.
+ * Modal on desktop, bottom sheet on mobile — an overlay and not a route, because navigating
+ * would unmount TreatmentWorkspace and destroy the in-progress draft.
  */
 export function VoiceReviewSheet({
   result,
@@ -78,10 +77,9 @@ export function VoiceReviewSheet({
       // The teeth row starts unticked whenever the recording produced no teeth of its own,
       // and a picked tooth that is not ticked applies nothing.
       teeth: true,
-      // The picked tooth has no prosthesis type, which makes the map unshippable. Leaving
-      // the row ticked would apply a map that `assertCompleteToothProsthesisMap` rejects
-      // at dispatch — the exact failure the never-auto-tick-incomplete rule exists to
-      // prevent. Only ever unticks: re-ticking is the clinician's call.
+      // A picked tooth has no prosthesis type, so the map is no longer shippable — leaving the
+      // row ticked would apply a map dispatch rejects. Only ever unticks; re-ticking is the
+      // clinician's call.
       prosthesis:
         prev.prosthesis &&
         withChosenTeeth(result, nextChosen).prosthesis?.complete !== false,
@@ -290,9 +288,8 @@ function Row({
 }
 
 /**
- * A bare `YYYY-MM-DD` is a *civil* date, but `new Date('2025-10-17')` parses it as UTC
- * midnight — which renders as the 16th for any viewer west of Greenwich. Build the date
- * from its parts so it means the same day everywhere.
+ * `new Date('2025-10-17')` parses a civil date as UTC midnight, which renders as the 16th
+ * west of Greenwich. Build it from its parts so it means the same day everywhere.
  */
 function civilDateToLocalDate(iso: string): Date {
   const [year, month, day] = iso.split('-').map(Number);

frontend/src/lib/api/voice.ts

@@ -22,8 +22,7 @@ export const voiceApi = {
     payload: ExtractVoicePayload,
     signal?: AbortSignal,
   ): Promise<{ success: boolean; data: VoiceExtractionResult }> => {
-    // The signal is forwarded so cancelling closes the connection, which aborts the
-    // metered vendor call server-side rather than letting it settle unseen.
+    // Forwarded so cancelling closes the connection; the controller turns that into an abort.
     const response = await apiClient.post('/voice/extract', payload, { signal });
     return response.data;
   },

frontend/src/lib/voice/audioFormat.ts

@@ -9,11 +9,9 @@ const PREFERRED_MIME_TYPES = [
 ] as const;
 
 /**
- * Pick a container this browser can record AND the backend accepts.
- *
- * Chrome and Android produce webm/opus; Safari and iPad produce mp4/aac. Both go to the
- * vendor unmodified, so there is no transcode step — but the choice still has to be made
- * at record time, and `isTypeSupported` is missing entirely on older Safari.
+ * Pick a container this browser can record AND the backend accepts. Chrome and Android give
+ * webm/opus, Safari and iPad mp4/aac; both go to the vendor unmodified, so there is no
+ * transcode step and the list is an intersection, not a preference.
  */
 export function pickRecordingMimeType(): string | null {
   if (typeof MediaRecorder === 'undefined') return null;

frontend/src/lib/voice/useVoiceCapture.ts

@@ -69,9 +69,8 @@ export function useVoiceCapture({
   /** getUserMedia is async; without this a permission granted after unmount leaks the mic. */
   const mountedRef = useRef(true);
   /**
-   * Set synchronously on click. `phase` does not become 'recording' until getUserMedia
-   * resolves, so without this a second click during the permission prompt would start a
-   * second stream and orphan the first — mic indicator lit, interval leaked.
+   * Set synchronously on click: `phase` only becomes 'recording' once getUserMedia resolves,
+   * so a second click during the permission prompt would orphan the first stream.
    */
   const startingRef = useRef(false);
 
@@ -139,9 +138,7 @@ export function useVoiceCapture({
   );
 
   const stop = useCallback(() => {
-    // No recorder means nothing will fire `onstop`, so nothing else will move the phase.
-    // Optional-chaining into a no-op here left the bar recording forever with a running
-    // timer, and only Cancel could get out of it.
+    // No recorder means nothing will fire `onstop`, so nothing else moves the phase.
     if (!recorderRef.current) {
       teardown();
       setPhase('idle');
@@ -158,8 +155,9 @@ export function useVoiceCapture({
   const onStart = useCallback(() => {
     if (phase !== 'idle' || startingRef.current) return;
     if (!isMediaRecorderSupported()) {
-      // Not a permission problem: this browser cannot record at all. Saying "microphone
-      // denied" sends the clinician to hunt for a permission nothing ever asked for.
+      // VOICE_UNSUPPORTED_FORMAT, not MIC_DENIED: nothing asked for a permission yet, and
+      // blaming the microphone sends the clinician into site settings for no reason. Same
+      // for the two paths below.
       onError(clientError('VOICE_UNSUPPORTED_FORMAT'));
       return;
     }
@@ -187,7 +185,6 @@ export function useVoiceCapture({
 
         const mimeType = pickRecordingMimeType();
         if (mimeType === null) {
-          // The browser records, but in no container the transcription API accepts.
           stream.getTracks().forEach((track) => track.stop());
           onError(clientError('VOICE_UNSUPPORTED_FORMAT'));
           return;
@@ -231,14 +228,10 @@ export function useVoiceCapture({
           if (maxMs != null && elapsed >= maxMs) stop();
         }, LEVEL_POLL_MS);
       } catch {
-        // `new MediaRecorder(...)` and `recorder.start()` both throw on some browsers,
-        // and by then the stream is already live. Without this the promise rejects
-        // unhandled, the UI sits at 'idle' with nothing shown, and the browser's
-        // recording indicator stays lit until the workspace unmounts.
+        // `new MediaRecorder()` and `recorder.start()` both throw on some browsers, and by
+        // then the stream is live — without this the mic indicator stays lit until unmount.
         teardown();
         setPhase('idle');
-        // The permission was already granted by this point — what failed is the recorder
-        // itself, so this is "this browser cannot record", not "you denied the mic".
         onError(clientError('VOICE_UNSUPPORTED_FORMAT'));
       } finally {
         startingRef.current = false;
@@ -248,8 +241,7 @@ export function useVoiceCapture({
 
   const onCancel = useCallback(() => {
     cancelledRef.current = true;
-    // Aborting closes the connection, which aborts the vendor call server-side. It is
-    // metered per minute, so letting it settle costs money for a result nobody sees.
+    // Aborting closes the connection, which aborts the vendor call server-side.
     abortRef.current?.abort();
     try {
       recorderRef.current?.stop();
@@ -283,10 +275,9 @@ function attachLevelMeter(
     source.connect(analyser);
 
     const data = new Uint8Array(analyser.frequencyBinCount);
-    // Sample every frame so a transient is not missed, but publish at LEVEL_POLL_MS.
-    // This hook lives in TreatmentWorkspace, so an unthrottled setLevel re-renders the
-    // details editor, the FDI chart and the lab panel on every animation frame — about
-    // 7,200 whole-tree renders across a two-minute recording.
+    // Sample every frame so a transient is not missed, publish at LEVEL_POLL_MS. The hook
+    // lives in TreatmentWorkspace, so an unthrottled setLevel is ~7,200 whole-tree renders
+    // across a two-minute recording.
     let peakSinceEmit = 0;
     let lastEmit = 0;
     const tick = (now: number) => {