docs: Consolidate coding rules and strengthen test policy

.claude/rules/coding-style.md

@@ -66,6 +66,47 @@ console.log('Workbook created successfully');
 
 Prefer placing the single authoritative log in the service layer; remove duplicate logs in route handlers that cover the same event.
 
+## No Hard-Coded Values
+
+Extract magic numbers and strings to named constants. Never embed literal values whose meaning is not self-evident from the type or immediate context.
+
+```typescript
+// Bad
+if (grade >= 11) { ... }
+
+const url = '/api/workbooks/submit';
+
+// Good
+const MIN_GRADE = 11;
+
+if (grade >= MIN_GRADE) { ... }
+
+const SUBMIT_URL = '/api/workbooks/submit';
+```
+
+Place constants at the top of the file, or in a dedicated `constants/` module when shared across files.
+
+## Function Ordering
+
+Within a file, order declarations as follows:
+
+1. Exported functions and classes (public API first)
+2. Internal helper functions (supporting the exports above)
+
+Shared helper functions (used by two or more exports) should be grouped at the end of the file.
+
+## Svelte 5: Prefer Official Docs Over Training Knowledge
+
+When Svelte 5 behavior is unclear, fetch the official docs directly via WebFetch instead of relying on training knowledge.
+
+URL pattern: `https://svelte.dev/docs/svelte/{section}`
+
+Examples:
+
+- `$effect` behavior → `https://svelte.dev/docs/svelte/$effect`
+- Stores usage → `https://svelte.dev/docs/svelte/stores`
+- Runes overview → `https://svelte.dev/docs/svelte/what-are-runes`
+
 ## Async Rollback: Capture State Before `await`
 
 Capture `$state` values before the first `await` for safe rollback. A concurrent update can overwrite the variable while awaiting:

.claude/rules/testing.md

@@ -13,6 +13,12 @@ paths:
 
 Write all test titles in English. Use descriptive sentences that state the expected behavior (e.g., `'returns empty array when workbooks is empty'`). Japanese is only acceptable in inline comments or fixture strings that represent real user-facing content.
 
+## Tests Ship with the Implementation
+
+Tests must be included in the same commit as the implementation they cover. "Add tests later" is not acceptable — a feature or fix is not done until its tests pass.
+
+If a task description does not mention tests, add them anyway for any non-trivial logic.
+
 ## Test Integrity
 
 - Never delete, comment out, or weaken assertions (e.g. `toEqual` → `toBeDefined`) to make tests pass