diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index db3e8f738..e7314ccbd 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -1,8 +1,12 @@
 # Changelog
 
 ## [Unreleased]
+
 ### Added
 
+- Deferred diagnostics support in LSP writethrough: `onDeferredDiagnostics` callback and `deferredSignal` in `WritethroughOptions` allow callers to receive diagnostics that arrive after the main 5-second timeout
+- Language detection for `.pm` (Perl modules), `.astro` (Astro framework), and special filenames `containerfile` and `justfile`
+- Workspace-scoped diagnostics and reload actions via `*` file parameter; `diagnostics` action now supports `*` for workspace-wide diagnostics across all configured servers
 - Socket-mode DAP adapter support for debuggers like dlv that communicate via network sockets instead of stdio; Linux uses unix domain sockets, macOS/other platforms use TCP with client-addr dialing
 - Improved extensionless binary debugging: native debuggers (gdb, lldb-dap) and adapters with root markers are now preferred over unrelated adapters like debugpy
 - Debug tool with DAP (Debug Adapter Protocol) support for launching and attaching debuggers, setting breakpoints, stepping through execution, inspecting threads/stack/variables, and evaluating expressions
@@ -20,6 +24,9 @@
 
 ### Changed
 
+- LSP diagnostics timeout reduced from 10 seconds to 5 seconds for faster feedback; slow diagnostics now fetch in background via deferred mechanism
+- Diagnostics action error messaging clarified: requires `file` parameter or `*` for workspace scope; improved guidance in error responses
+- Workspace symbols and reload actions now accept `*` to operate across all configured servers instead of requiring a file path
 - DAP session initialization now subscribes to stop events before launching/attaching to avoid missing stopOnEntry events
 - Stack frame fetching moved outside the event dispatch loop to prevent deadlocks and improve responsiveness
 - Evaluate requests now default to the top stopped frame when frameId is not explicitly provided
diff --git a/packages/coding-agent/src/lsp/index.ts b/packages/coding-agent/src/lsp/index.ts
index 72cf86b99..250e44b93 100644
--- a/packages/coding-agent/src/lsp/index.ts
+++ b/packages/coding-agent/src/lsp/index.ts
@@ -692,8 +692,25 @@ export interface WritethroughOptions {
 	enableFormat?: boolean;
 	/** Whether to get LSP diagnostics after writing */
 	enableDiagnostics?: boolean;
+	/** Called when diagnostics arrive after the main timeout. */
+	onDeferredDiagnostics?: (diagnostics: FileDiagnosticsResult) => void;
+	/** Signal to cancel a pending deferred diagnostics fetch. */
+	deferredSignal?: AbortSignal;
 }
 
+/** Internal resolved form of {@link WritethroughOptions} that the writethrough machinery operates on. */
+type ResolvedWritethroughOptions = {
+	enableFormat: boolean;
+	enableDiagnostics: boolean;
+};
+
+/** Per-file deferred LSP diagnostics wiring for {@link WritethroughCallback}. */
+export type WritethroughDeferredHandle = {
+	onDeferredDiagnostics: (diagnostics: FileDiagnosticsResult) => void;
+	signal: AbortSignal;
+	finalize: (diagnostics: FileDiagnosticsResult | undefined) => void;
+};
+
 /** Callback type for the LSP writethrough */
 export type WritethroughCallback = (
 	dst: string,
@@ -701,6 +718,7 @@ export type WritethroughCallback = (
 	signal?: AbortSignal,
 	file?: BunFile,
 	batch?: LspWritethroughBatchRequest,
+	getDeferred?: (dst: string) => WritethroughDeferredHandle | undefined,
 ) => Promise<FileDiagnosticsResult | undefined>;
 
 /** No-op writethrough callback */
@@ -709,6 +727,8 @@ export async function writethroughNoop(
 	content: string,
 	_signal?: AbortSignal,
 	file?: BunFile,
+	_batch?: LspWritethroughBatchRequest,
+	_getDeferred?: (dst: string) => WritethroughDeferredHandle | undefined,
 ): Promise<FileDiagnosticsResult | undefined> {
 	if (file) {
 		await file.write(content);
@@ -731,12 +751,12 @@ interface LspWritethroughBatchRequest {
 
 interface LspWritethroughBatchState {
 	entries: Map<string, PendingWritethrough>;
-	options: Required<WritethroughOptions>;
+	options: ResolvedWritethroughOptions;
 }
 
 const writethroughBatches = new Map<string, LspWritethroughBatchState>();
 
-function getOrCreateWritethroughBatch(id: string, options: Required<WritethroughOptions>): LspWritethroughBatchState {
+function getOrCreateWritethroughBatch(id: string, options: ResolvedWritethroughOptions): LspWritethroughBatchState {
 	const existing = writethroughBatches.get(id);
 	if (existing) {
 		existing.options.enableFormat ||= options.enableFormat;
@@ -787,7 +807,7 @@ function summarizeDiagnosticMessages(messages: string[]): { summary: string; err
 
 function mergeDiagnostics(
 	results: Array<FileDiagnosticsResult | undefined>,
-	options: Required<WritethroughOptions>,
+	options: ResolvedWritethroughOptions,
 ): FileDiagnosticsResult | undefined {
 	const messages: string[] = [];
 	const servers = new Set<string>();
@@ -841,13 +861,41 @@ function mergeDiagnostics(
 	};
 }
 
+async function scheduleDeferredDiagnosticsFetch(args: {
+	dst: string;
+	cwd: string;
+	servers: Array<[string, ServerConfig]>;
+	minVersions: ServerVersionMap | undefined;
+	expectedDocumentVersions: ServerVersionMap | undefined;
+	signal: AbortSignal;
+	callback: (diagnostics: FileDiagnosticsResult) => void;
+}): Promise<void> {
+	try {
+		const deferredTimeout = AbortSignal.timeout(25_000);
+		const combined = AbortSignal.any([args.signal, deferredTimeout]);
+		const diagnostics = await getDiagnosticsForFile(args.dst, args.cwd, args.servers, {
+			signal: combined,
+			minVersions: args.minVersions,
+			expectedDocumentVersions: args.expectedDocumentVersions,
+		});
+		if (args.signal.aborted || diagnostics === undefined) return;
+		args.callback(diagnostics);
+	} catch {
+		// Cancelled or LSP gave up; silently discard.
+	}
+}
+
 async function runLspWritethrough(
 	dst: string,
 	content: string,
 	cwd: string,
-	options: Required<WritethroughOptions>,
+	options: ResolvedWritethroughOptions,
 	signal?: AbortSignal,
 	file?: BunFile,
+	deferred?: {
+		onDeferredDiagnostics: (diagnostics: FileDiagnosticsResult) => void;
+		signal: AbortSignal;
+	},
 ): Promise<FileDiagnosticsResult | undefined> {
 	const { enableFormat, enableDiagnostics } = options;
 	const config = getConfig(cwd);
@@ -870,7 +918,7 @@ async function runLspWritethrough(
 	let diagnostics: FileDiagnosticsResult | undefined;
 	let timedOut = false;
 	try {
-		const timeoutSignal = AbortSignal.timeout(10_000);
+		const timeoutSignal = AbortSignal.timeout(5_000);
 		timeoutSignal.addEventListener(
 			"abort",
 			() => {
@@ -927,6 +975,18 @@ async function runLspWritethrough(
 		if (timedOut) {
 			formatter = undefined;
 			diagnostics = undefined;
+			// Schedule background diagnostic fetch if caller wants deferred results
+			if (deferred && !deferred.signal.aborted && enableDiagnostics) {
+				void scheduleDeferredDiagnosticsFetch({
+					dst,
+					cwd,
+					servers,
+					minVersions,
+					expectedDocumentVersions,
+					signal: deferred.signal,
+					callback: deferred.onDeferredDiagnostics,
+				});
+			}
 		}
 		await getWritePromise();
 	}
@@ -947,22 +1007,32 @@ async function runLspWritethrough(
 async function flushWritethroughBatch(
 	batch: PendingWritethrough[],
 	cwd: string,
-	options: Required<WritethroughOptions>,
+	options: ResolvedWritethroughOptions,
 	signal?: AbortSignal,
+	getDeferred?: (dst: string) => WritethroughDeferredHandle | undefined,
 ): Promise<FileDiagnosticsResult | undefined> {
 	if (batch.length === 0) {
 		return undefined;
 	}
 	const results: Array<FileDiagnosticsResult | undefined> = [];
 	for (const entry of batch) {
-		results.push(await runLspWritethrough(entry.dst, entry.content, cwd, options, signal, entry.file));
+		const bundle = getDeferred?.(entry.dst);
+		const deferredInner =
+			bundle &&
+			({
+				onDeferredDiagnostics: bundle.onDeferredDiagnostics,
+				signal: bundle.signal,
+			} as const);
+		const diag = await runLspWritethrough(entry.dst, entry.content, cwd, options, signal, entry.file, deferredInner);
+		bundle?.finalize(diag);
+		results.push(diag);
 	}
 	return mergeDiagnostics(results, options);
 }
 
 /** Create a writethrough callback for LSP aware write operations */
 export function createLspWritethrough(cwd: string, options?: WritethroughOptions): WritethroughCallback {
-	const resolvedOptions: Required<WritethroughOptions> = {
+	const resolvedOptions: ResolvedWritethroughOptions = {
 		enableFormat: options?.enableFormat ?? false,
 		enableDiagnostics: options?.enableDiagnostics ?? false,
 	};
@@ -975,9 +1045,19 @@ export function createLspWritethrough(cwd: string, options?: WritethroughOptions
 		signal?: AbortSignal,
 		file?: BunFile,
 		batch?: LspWritethroughBatchRequest,
+		getDeferred?: (dst: string) => WritethroughDeferredHandle | undefined,
 	) => {
 		if (!batch) {
-			return runLspWritethrough(dst, content, cwd, resolvedOptions, signal, file);
+			const bundle = getDeferred?.(dst);
+			const deferredInner =
+				bundle &&
+				({
+					onDeferredDiagnostics: bundle.onDeferredDiagnostics,
+					signal: bundle.signal,
+				} as const);
+			const diagnostics = await runLspWritethrough(dst, content, cwd, resolvedOptions, signal, file, deferredInner);
+			bundle?.finalize(diagnostics);
+			return diagnostics;
 		}
 
 		const state = getOrCreateWritethroughBatch(batch.id, resolvedOptions);
@@ -989,7 +1069,7 @@ export function createLspWritethrough(cwd: string, options?: WritethroughOptions
 		}
 
 		writethroughBatches.delete(batch.id);
-		return flushWritethroughBatch(Array.from(state.entries.values()), cwd, state.options, signal);
+		return flushWritethroughBatch(Array.from(state.entries.values()), cwd, state.options, signal, getDeferred);
 	};
 }
 
@@ -1054,8 +1134,8 @@ export class LspTool implements AgentTool<typeof lspSchema, LspToolDetails, Them
 
 		// Diagnostics can be batch or single-file - queries all applicable servers
 		if (action === "diagnostics") {
-			if (!file) {
-				// No file specified - run workspace diagnostics
+			if (file === "*") {
+				// `*` => run workspace diagnostics across all configured servers
 				const result = await runWorkspaceDiagnostics(this.session.cwd, signal);
 				return {
 					content: [
@@ -1068,6 +1148,18 @@ export class LspTool implements AgentTool<typeof lspSchema, LspToolDetails, Them
 				};
 			}
 
+			if (!file) {
+				return {
+					content: [
+						{
+							type: "text",
+							text: "Error: file parameter required. Use `*` for workspace-wide diagnostics or a path/glob for specific files.",
+						},
+					],
+					details: { action, success: false, request: params },
+				};
+			}
+
 			let targets: string[];
 			let truncatedGlobTargets = false;
 			if (hasGlobPattern(file)) {
@@ -1186,17 +1278,24 @@ export class LspTool implements AgentTool<typeof lspSchema, LspToolDetails, Them
 			};
 		}
 
-		const requiresFile = !file && action !== "symbols" && action !== "reload";
+		// `*` means workspace scope for symbols/reload; other actions need a concrete file.
+		const isWorkspace = file === "*";
+		const requiresFile = !file && action !== "reload";
 
 		if (requiresFile) {
 			return {
-				content: [{ type: "text", text: "Error: file parameter required for this action" }],
+				content: [
+					{
+						type: "text",
+						text: "Error: file parameter required. Use `*` for workspace scope where supported.",
+					},
+				],
 				details: { action, success: false },
 			};
 		}
 
-		const resolvedFile = file ? resolveToCwd(file, this.session.cwd) : null;
-		if (action === "symbols" && !resolvedFile) {
+		const resolvedFile = file && !isWorkspace ? resolveToCwd(file, this.session.cwd) : null;
+		if (action === "symbols" && (isWorkspace || !resolvedFile)) {
 			const normalizedQuery = query?.trim();
 			if (!normalizedQuery) {
 				return {
@@ -1268,7 +1367,7 @@ export class LspTool implements AgentTool<typeof lspSchema, LspToolDetails, Them
 			};
 		}
 
-		if (action === "reload" && !resolvedFile) {
+		if (action === "reload" && (isWorkspace || !resolvedFile)) {
 			const servers = getLspServers(config);
 			if (servers.length === 0) {
 				return {
diff --git a/packages/coding-agent/src/lsp/utils.ts b/packages/coding-agent/src/lsp/utils.ts
index 89e44e721..791234b7e 100644
--- a/packages/coding-agent/src/lsp/utils.ts
+++ b/packages/coding-agent/src/lsp/utils.ts
@@ -52,6 +52,7 @@ const LANGUAGE_MAP: Record<string, string> = {
 	".zsh": "shellscript",
 	".fish": "fish",
 	".pl": "perl",
+	".pm": "perl",
 	".php": "php",
 
 	// JVM languages
@@ -76,6 +77,7 @@ const LANGUAGE_MAP: Record<string, string> = {
 	".less": "less",
 	".vue": "vue",
 	".svelte": "svelte",
+	".astro": "astro",
 
 	// Data formats
 	".json": "json",
@@ -142,12 +144,15 @@ export function detectLanguageId(filePath: string): string {
 	const basename = path.basename(filePath).toLowerCase();
 
 	// Handle special filenames
-	if (basename === "dockerfile" || basename.startsWith("dockerfile.")) {
+	if (basename === "dockerfile" || basename.startsWith("dockerfile.") || basename === "containerfile") {
 		return "dockerfile";
 	}
 	if (basename === "makefile" || basename === "gnumakefile") {
 		return "makefile";
 	}
+	if (basename === "justfile") {
+		return "just";
+	}
 	if (basename === "cmakelists.txt" || ext === ".cmake") {
 		return "cmake";
 	}