fix(tool-edit-file): lazy LSP service lookup — diagnostics now actually work

The previous fix (e03a96e) wrapped getService in try/catch to prevent the
activation crash, but that wasn't enough: tool-edit-file activates at position
5 in CORE_EXTENSIONS while lsp activates at position 20. So getService ALWAYS
threw at activation time, lspService was ALWAYS undefined, and the diagnostics
hook was NEVER wired — edits succeeded but never showed LSP feedback.

Fix: make the LSP service lookup LAZY — defer it to edit time (when the tool is
actually called), not activation time. By then all extensions have activated.
The diagnostics function tries getService on each edit call; if LSP isn't
loaded, it returns a no-op (graceful degradation).

1 files changed, 23 insertions, 20 deletions

diff --git a/packages/tool-edit-file/src/extension.ts b/packages/tool-edit-file/src/extension.ts
index 9be53da..3929634 100644
--- a/packages/tool-edit-file/src/extension.ts
+++ b/packages/tool-edit-file/src/extension.ts
@@ -14,26 +14,29 @@ export const extension: Extension = {
 		contributes: { tools: ["edit_file"] },
 	},
 	activate(host) {
-		// Optional LSP integration: if the lsp extension is loaded AND has
-		// activated before us, wire its getDiagnostics service as the post-edit
-		// diagnostics hook. If absent (not loaded, or activates after us), edits
-		// proceed without diagnostics (graceful degradation).
-		let lspService: LspService | undefined;
-		try {
-			lspService = host.getService(lspServiceHandle);
-		} catch {
-			lspService = undefined;
-		}
-		const diagnostics: DiagnosticsHook | undefined = lspService
-			? async (opts) =>
-					lspService.getDiagnostics({
-						filePath: opts.filePath,
-						text: opts.text,
-						cwd: opts.cwd,
-						timeoutMs: 60_000,
-						minSeverity: 2, // errors + warnings only
-					})
-			: undefined;
+		// Lazy LSP lookup: the LSP extension activates AFTER us in the
+		// CORE_EXTENSIONS array, so host.getService would throw at activation
+		// time. Instead, defer the lookup to edit time — by then all extensions
+		// have activated. If LSP isn't loaded, the try/catch returns a no-op
+		// (graceful degradation: edits proceed without diagnostics).
+		const diagnostics: DiagnosticsHook = async (opts) => {
+			let lspService: LspService | undefined;
+			try {
+				lspService = host.getService(lspServiceHandle);
+			} catch {
+				return { formatted: "", slow: false, timedOut: false };
+			}
+			if (!lspService) {
+				return { formatted: "", slow: false, timedOut: false };
+			}
+			return lspService.getDiagnostics({
+				filePath: opts.filePath,
+				text: opts.text,
+				cwd: opts.cwd,
+				timeoutMs: 60_000,
+				minSeverity: 2, // errors + warnings only
+			});
+		};
 
 		host.defineTool(createEditFileTool(process.cwd(), diagnostics));
 	},