implement registration-confirmation-email

- Add qrbill and pillow dependencies for Swiss QR-bill PNG generation
- Add _STRINGS_DE / _STRINGS_EN bilingual string tables to AdminNotifier
- Add _generate_qr_bill_png(): Swiss QR code with cross overlay (PNG bytes)
- Add _build_parent_html(): HTML confirmation with inline cid:qrbill image
- Add _build_parent_text(): plain-text fallback with IBAN in full
- Add notify_parent(): multipart/mixed MIME email to parent on completion
- Persist metadata.language in _build_record() in json_store.py
- Wire notify_parent() into src/agent/core.py and chat_app.py completion events
- Add 9 tests for notify_parent, _generate_qr_bill_png, language fallback
- Update tasks.md: tasks 1–5 complete; task 6 (smoke test) remains manual

112 tests passing.

https://claude.ai/code/session_01LjjK7RjKVnC8bETtccfgna

openspec/changes/registration-confirmation-email/tasks.md

@@ -1,26 +1,26 @@
 ## 1. Add `qrbill` Dependency
 
-- [ ] 1.1 Add `qrbill` to `[project.dependencies]` in `pyproject.toml`
-- [ ] 1.2 Run `uv lock` to update the lockfile
-- [ ] 1.3 Verify `qrbill` imports successfully in a smoke test or REPL
+- [x] 1.1 Add `qrbill` to `[project.dependencies]` in `pyproject.toml`
+- [x] 1.2 Run `uv lock` to update the lockfile
+- [x] 1.3 Verify `qrbill` imports successfully in a smoke test or REPL
 
 ## 2. Persist Language in Registration Record
 
-- [ ] 2.1 Update `ConversationStore._build_record()` in `src/storage/json_store.py` to include `language` from `state.language` in the `metadata` dict
-- [ ] 2.2 Update `ConversationStore.save_registration()` and `save_registration_version()` signatures to accept/forward `state` (already does — confirm `_build_record` receives the full state)
-- [ ] 2.3 Add a test in `tests/test_storage.py` asserting that the saved record's `metadata.language` matches `state.language`
+- [x] 2.1 Update `ConversationStore._build_record()` in `src/storage/json_store.py` to include `language` from `state.language` in the `metadata` dict
+- [x] 2.2 Update `ConversationStore.save_registration()` and `save_registration_version()` signatures to accept/forward `state` (already does — confirm `_build_record` receives the full state)
+- [x] 2.3 Add a test in `tests/test_storage.py` asserting that the saved record's `metadata.language` matches `state.language`
 
 ## 3. Add `notify_parent()` to `AdminNotifier`
 
-- [ ] 3.1 Add a `_generate_qr_bill_png()` static/class method to `AdminNotifier` using `qrbill` with fixed payment data:
+- [x] 3.1 Add a `_generate_qr_bill_png()` static/class method to `AdminNotifier` using `qrbill` with fixed payment data:
   - IBAN: `CH14 0900 0000 4930 8018 8`
   - Payee: Familienverein Fällanden Spielgruppen, Huebwisstrase 5, 8117 Fällanden
   - Amount: `80.00`, Currency: `CHF`, Reference type: NON
   - Returns raw PNG `bytes`
-- [ ] 3.2 Add bilingual string template dicts `_STRINGS_DE` and `_STRINGS_EN` (module-level constants) covering all user-visible strings in the confirmation email (subject, section headers, fee labels, payment instructions text, closing)
-- [ ] 3.3 Add `_build_parent_html()` method: renders full HTML confirmation email body using the appropriate string dict, embedding the QR image via `cid:qrbill`; includes registration summary and both monthly fee (informational) and CHF 80 registration fee (with IBAN text + QR reference)
-- [ ] 3.4 Add `_build_parent_text()` method: renders the plain-text fallback, including all summary fields and IBAN/payee details in plain text (no image)
-- [ ] 3.5 Add `notify_parent()` public method:
+- [x] 3.2 Add bilingual string template dicts `_STRINGS_DE` and `_STRINGS_EN` (module-level constants) covering all user-visible strings in the confirmation email (subject, section headers, fee labels, payment instructions text, closing)
+- [x] 3.3 Add `_build_parent_html()` method: renders full HTML confirmation email body using the appropriate string dict, embedding the QR image via `cid:qrbill`; includes registration summary and both monthly fee (informational) and CHF 80 registration fee (with IBAN text + QR reference)
+- [x] 3.4 Add `_build_parent_text()` method: renders the plain-text fallback, including all summary fields and IBAN/payee details in plain text (no image)
+- [x] 3.5 Add `notify_parent()` public method:
   - Parameters: `registration: RegistrationData`, `language: str = "de"`
   - Select string dict based on `language`; fall back to `"de"` for unknown values
   - Call `_generate_qr_bill_png()` to get PNG bytes
@@ -30,20 +30,20 @@
 
 ## 4. Wire `notify_parent()` into Completion Events
 
-- [ ] 4.1 In `src/agent/core.py` `_handle_registration()`: after the existing `notify_admin()` try/except block, add a parallel try/except block calling `self._notifier.notify_parent(registration=state.registration, language=state.language)`
-- [ ] 4.2 In `chat_app.py` `on_message()`: after the existing `notify_admin()` call inside the completion block, add a parallel try/except block calling `_notifier.notify_parent(registration=state.registration, language=state.language)`
-- [ ] 4.3 Verify both call sites log a warning (not an exception) on failure, and the registration completion path continues normally
+- [x] 4.1 In `src/agent/core.py` `_handle_registration()`: after the existing `notify_admin()` try/except block, add a parallel try/except block calling `self._notifier.notify_parent(registration=state.registration, language=state.language)`
+- [x] 4.2 In `chat_app.py` `on_message()`: after the existing `notify_admin()` call inside the completion block, add a parallel try/except block calling `_notifier.notify_parent(registration=state.registration, language=state.language)`
+- [x] 4.3 Verify both call sites log a warning (not an exception) on failure, and the registration completion path continues normally
 
 ## 5. Tests
 
-- [ ] 5.1 Add `tests/test_notifier.py` tests for `notify_parent()`:
+- [x] 5.1 Add `tests/test_notifier.py` tests for `notify_parent()`:
   - `test_notify_parent_calls_send`: mock `_send` and assert it is called with `to=[parent_email]`
   - `test_notify_parent_german_subject`: assert subject contains German text when `language="de"`
   - `test_notify_parent_english_subject`: assert subject contains English text when `language="en"`
   - `test_notify_parent_unknown_language_falls_back_to_de`: assert `language="fr"` produces German subject
   - `test_notify_parent_no_smtp_skips_send`: when `smtp_host=""`, `_send` is NOT called
-- [ ] 5.2 Add a test asserting that the plain-text body contains the IBAN string `CH14` when `smtp_host` is empty (inspecting log or body build directly)
-- [ ] 5.3 Add a test for `_generate_qr_bill_png()` asserting it returns `bytes` with non-zero length (requires `qrbill` installed)
+- [x] 5.2 Add a test asserting that the plain-text body contains the IBAN string `CH14` when `smtp_host` is empty (inspecting log or body build directly)
+- [x] 5.3 Add a test for `_generate_qr_bill_png()` asserting it returns `bytes` with non-zero length (requires `qrbill` installed)
 
 ## 6. Manual Smoke Test