Make the morpheme-break reset explicit: rename Delete, and reset on the bare surface form

AGENTS.md

@@ -113,6 +113,10 @@ Jest with ts-jest, jsdom environment. PAPI is fully mocked in `__mocks__/`. Cove
 
 `@papi/backend` and `@papi/frontend` mocks are mutually exclusive: backend tests use `papi-backend.ts`, WebView tests use `papi-frontend.ts` + `papi-frontend-react.ts`. Each mock file ends with `export {}` so TypeScript treats it as a module.
 
+### Testing hooks
+
+Test context hooks and dispatchers directly with `renderHook` + a `wrapper`, not a throwaway button-and-click component. See `renderStoreHook` in [AnalysisStore.test.tsx](src/__tests__/components/AnalysisStore.test.tsx) for the provider-wrapping pattern: return the hooks under test from the callback, drive dispatchers inside `act(...)`, and assert on state read off `result.current`. Reserve rendered components for behavior that genuinely needs the DOM — re-render / render-count assertions and mount/unmount lifecycle.
+
 ### Branches not worth testing
 
 100% coverage is enforced, but coverage is a floor, not a goal — chasing it produces low-value tests that bloat the suite and slow it down. Do **not** write a dedicated test for a branch whose only purpose is to satisfy the coverage gate when the branch carries no real behavior. Such branches should instead be excluded from coverage (via `/* v8 ignore next */` with a one-line reason, or the explicit exclusions in the Jest config) rather than tested. Branches not worth a dedicated test:

contributions/localizedStrings.json

@@ -37,9 +37,12 @@
       "%interlinearizer_glossInput_placeholder%": "gloss",
       "%interlinearizer_freeTranslationInput_placeholder%": "Free translation",
       "%interlinearizer_morphemeEditor_splitLabel%": "Split into morphemes",
-      "%interlinearizer_morphemeEditor_delete%": "Delete",
+      "%interlinearizer_morphemeEditor_reset%": "Reset",
       "%interlinearizer_morphemeEditor_cancel%": "Cancel",
       "%interlinearizer_morphemeEditor_done%": "Done",
+      "%interlinearizer_morphemeEditor_emptyHint%": "Enter morpheme forms separated by spaces",
+      "%interlinearizer_morphemeEditor_confirmResetPrompt%": "Discard this breakdown and its glosses?",
+      "%interlinearizer_morphemeEditor_confirmResetAction%": "Reset",
       "%interlinearizer_morphemeGloss_label%": "Gloss for morpheme {form}",
       "%interlinearizer_tokenChip_editMorphemes%": "Edit morpheme breakdown for {token}",
       "%interlinearizer_tokenChip_defineMorphemes%": "Define morpheme breakdown for {token}",