refactor(transcribe): extract t-mark + draw-cue policy into tested helpers (#327)

Review follow-up (Sara, fast-follow): the t no-active-region guard and the
draw-cue arm/disarm rule lived inline in the page with no direct coverage.
Extracted to pure resolveTrainingMark() (no-op when no region; recognition
enrolled flip) and canArmDraw()/shouldDisarmDraw(), each with unit tests
(10 cases total). The page now arms the draw cue only via canArmDraw and
disarms via shouldDisarmDraw, and routes t through resolveTrainingMark.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/lib/document/transcription/drawCue.spec.ts

@@ -0,0 +1,14 @@
+import { describe, it, expect } from 'vitest';
+import { canArmDraw, shouldDisarmDraw } from './drawCue';
+
+describe('draw cue policy', () => {
+	it('arms only in edit mode', () => {
+		expect(canArmDraw('edit')).toBe(true);
+		expect(canArmDraw('read')).toBe(false);
+	});
+
+	it('disarms in every mode except edit', () => {
+		expect(shouldDisarmDraw('read')).toBe(true);
+		expect(shouldDisarmDraw('edit')).toBe(false);
+	});
+});

frontend/src/lib/document/transcription/drawCue.ts

@@ -0,0 +1,20 @@
+/**
+ * Policy for the "draw a new region" keyboard cue (the `n` shortcut) in the
+ * transcribe panel — issue #327.
+ *
+ * The cue is only valid while editing: `n` arms it in edit mode, and it must
+ * clear when a region is drawn or when the panel leaves edit mode. Pure so both
+ * rules are testable without mounting the page.
+ */
+
+type PanelMode = 'read' | 'edit';
+
+/** The draw cue may only be armed while in edit mode. */
+export function canArmDraw(panelMode: PanelMode): boolean {
+	return panelMode === 'edit';
+}
+
+/** Leaving edit mode must disarm the draw cue. */
+export function shouldDisarmDraw(panelMode: PanelMode): boolean {
+	return !canArmDraw(panelMode);
+}

frontend/src/lib/document/transcription/trainingMark.spec.ts

@@ -0,0 +1,30 @@
+import { describe, it, expect } from 'vitest';
+import { resolveTrainingMark, RECOGNITION_TRAINING_LABEL } from './trainingMark';
+
+describe('resolveTrainingMark', () => {
+	it('is a no-op (null) when no region is active', () => {
+		expect(resolveTrainingMark(null, [])).toBe(null);
+		expect(resolveTrainingMark(null, [RECOGNITION_TRAINING_LABEL])).toBe(null);
+	});
+
+	it('enrols recognition training when a region is active and not yet enrolled', () => {
+		expect(resolveTrainingMark('ann-1', [])).toEqual({
+			label: RECOGNITION_TRAINING_LABEL,
+			enrolled: true
+		});
+	});
+
+	it('un-enrols when recognition training is already enrolled', () => {
+		expect(resolveTrainingMark('ann-1', [RECOGNITION_TRAINING_LABEL])).toEqual({
+			label: RECOGNITION_TRAINING_LABEL,
+			enrolled: false
+		});
+	});
+
+	it('ignores unrelated document training labels', () => {
+		expect(resolveTrainingMark('ann-1', ['KURRENT_SEGMENTATION'])).toEqual({
+			label: RECOGNITION_TRAINING_LABEL,
+			enrolled: true
+		});
+	});
+});

frontend/src/lib/document/transcription/trainingMark.ts

@@ -0,0 +1,31 @@
+/**
+ * "Mark for training" (the `t` shortcut) decision logic — issue #327.
+ *
+ * Training enrollment is document-level — two fixed script-type chips
+ * (KURRENT_RECOGNITION / KURRENT_SEGMENTATION); there is no per-region training
+ * flag yet (that arrives with #321). `t` toggles the primary recognition
+ * enrollment and is a silent no-op unless a region is active, so it reads as an
+ * action on the region the transcriber is working on.
+ *
+ * Pure so the no-op-when-no-region guard and the enrolled flip are testable
+ * without mounting the page.
+ */
+export const RECOGNITION_TRAINING_LABEL = 'KURRENT_RECOGNITION';
+
+export type TrainingMarkToggle = { label: string; enrolled: boolean };
+
+/**
+ * Decide the recognition-training toggle for the active region, or null when no
+ * region is active (the `t` shortcut is then a silent no-op).
+ *
+ * @param activeAnnotationId the currently active region, or null
+ * @param currentLabels the document's currently enrolled training labels
+ */
+export function resolveTrainingMark(
+	activeAnnotationId: string | null,
+	currentLabels: readonly string[]
+): TrainingMarkToggle | null {
+	if (!activeAnnotationId) return null;
+	const enrolled = !currentLabels.includes(RECOGNITION_TRAINING_LABEL);
+	return { label: RECOGNITION_TRAINING_LABEL, enrolled };
+}

frontend/src/routes/documents/[id]/+page.svelte

@@ -13,6 +13,8 @@ import { transcribeShortcuts } from '$lib/shared/actions/transcribeShortcuts';
 import { createOcrJob } from '$lib/ocr/useOcrJob.svelte';
 import { createTranscriptionBlocks } from '$lib/document/transcription/useTranscriptionBlocks.svelte';
 import { stepRegion } from '$lib/document/transcription/regionNavigation';
+import { resolveTrainingMark } from '$lib/document/transcription/trainingMark';
+import { canArmDraw, shouldDisarmDraw } from '$lib/document/transcription/drawCue';
 import { createFileLoader } from '$lib/document/viewer/useFileLoader.svelte';
 import { scrollToCommentFromQuery } from '$lib/shared/utils/deepLinkScroll';
 import { getConfirmService } from '$lib/shared/services/confirm.svelte';
@@ -112,17 +114,9 @@ function toggleMode() {
 	if (canWrite) panelMode = panelMode === 'read' ? 'edit' : 'read';
 }
 
-// Training enrollment is document-level — two fixed script-type chips
-// (KURRENT_RECOGNITION / KURRENT_SEGMENTATION); there is no per-region training
-// flag (that would arrive with #321). "t" toggles the primary recognition
-// enrollment and stays a no-op unless a region is active, so it reads as an
-// action on the region the transcriber is working on.
-const RECOGNITION_TRAINING_LABEL = 'KURRENT_RECOGNITION';
-
 function toggleTrainingMark() {
-	if (!activeAnnotationId) return;
-	const enrolled = !(doc.trainingLabels ?? []).includes(RECOGNITION_TRAINING_LABEL);
-	transcription.toggleTrainingLabel(RECOGNITION_TRAINING_LABEL, enrolled);
+	const toggle = resolveTrainingMark(activeAnnotationId, doc.trainingLabels ?? []);
+	if (toggle) transcription.toggleTrainingLabel(toggle.label, toggle.enrolled);
 }
 
 function deleteCurrentRegion() {
@@ -131,7 +125,7 @@ function deleteCurrentRegion() {
 
 // Disarm the draw cue whenever we leave edit mode.
 $effect(() => {
-	if (panelMode !== 'edit') drawArmed = false;
+	if (shouldDisarmDraw(panelMode)) drawArmed = false;
 });
 
 const shortcutOptions = {
@@ -142,7 +136,9 @@ const shortcutOptions = {
 	goToPrevRegion: () => goToRegion(-1),
 	toggleMode,
 	closePanel: () => (transcribeMode = false),
-	startDrawMode: () => (drawArmed = true),
+	startDrawMode: () => {
+		if (canArmDraw(panelMode)) drawArmed = true;
+	},
 	toggleTrainingMark,
 	deleteCurrentRegion,
 	openCheatsheet: () => (cheatsheetOpen = true)