feat(coding-agent): added matcherDigest hook for TTSR wire-format normalization

- Added optional `AgentTool.matcherDigest(args)` hook so tools can expose plain source text instead of wire-encoded arguments to TTSR rule matchers.
- Implemented `matcherDigest` on edit (all modes: hashline, patch, apply_patch, replace) and write tools, stripping patch prefixes and JSON escaping.
- Added `TtsrManager.checkSnapshot()` to replace the scoped buffer with a tool digest rather than appending raw deltas.
- Fixed TTSR conditions never matching streamed edit/write calls whose wire format obscured real content.

packages/coding-agent/src/tools/write.ts

@@ -273,6 +273,12 @@ export class WriteTool implements AgentTool<typeof writeSchema, WriteToolDetails
 	readonly loadMode = "discoverable";
 	readonly summary = "Write content to a file (creates or overwrites)";
 
+	/** Stream matchers should see the real file content, not its JSON-escaped argument encoding. */
+	matcherDigest(args: unknown): string | undefined {
+		const content = (args as Partial<WriteParams>).content;
+		return typeof content === "string" ? content : undefined;
+	}
+
 	readonly #writethrough: WritethroughCallback;
 
 	constructor(private readonly session: ToolSession) {