Function Host Debugger View by nturinski · Pull Request #4883 · microsoft/vscode-azurefunctions

nturinski · 2026-01-14T22:56:18Z

This PR adds a Function Host Debug view to the Azure Functions extension. The view appears in the Run and Debug panel and lists running Function Host tasks along with their recent error output.

A new tree view provider backs this view and supplies nodes for active hosts and error entries. The view includes commands to refresh the data, clear recorded errors, view or copy recent logs, and send an error to Copilot. These commands are available from the view toolbar and node context menus.

The PR also introduces a setting to always show the Function Host Debug view, regardless of context.

Supporting changes include exporting shared utilities for identifying host error logs and cleaning log output, extending command handling to accept argument arrays, and updating the Functions task provider to allow additional CLI arguments in task definitions.

No host running (only visible if always show setting is enabled)

Function host running with no errors

Function host running with an error

Location of Ask Copilot context menu

Co-authored-by: Copilot <[email protected]>

…ft/vscode-azurefunctions into nat/fileBasedPickProcess

Co-authored-by: Copilot <[email protected]>

…ft/vscode-azurefunctions into nat/fileBasedPickProcess

…ions into nat/fileBasedPickProcess

…ft/vscode-azurefunctions into nat/fileBasedPickProcess

…ions into nat/fileBasedPickProcess

Copilot

Pull request overview

This PR adds a Function Host Debug view to the Azure Functions extension, providing developers with visibility into running Function Host tasks and their error output directly in the Run and Debug panel.

Changes:

Adds a new tree view in the Debug panel showing running Function Host tasks with their errors
Implements ANSI stripping utilities and error log detection based on terminal color codes
Integrates GitHub Copilot Chat for AI-assisted error diagnosis
Adds commands for viewing/copying logs and clearing errors
Extends task provider to support additional CLI arguments in task definitions

Reviewed changes

Copilot reviewed 16 out of 17 changed files in this pull request and generated 14 comments.

Show a summary per file

File	Description
src/debug/FunctionHostDebugView.ts	Tree data provider for the debug view, handles node creation and hierarchy
src/debug/registerFunctionHostDebugView.ts	Registers view commands (refresh, clear errors, show logs, ask Copilot) and handlers
src/funcCoreTools/funcHostTask.ts	Tracks running tasks, captures terminal output streams, detects and stores error logs
src/funcCoreTools/funcHostErrorUtils.ts	Utilities for identifying error logs via ANSI codes and extracting error context
src/utils/ansiUtils.ts	ANSI escape sequence removal for clean text presentation
src/utils/copilotChat.ts	Best-effort integration to open Copilot Chat with pre-filled prompts
src/debug/FuncTaskProvider.ts	Extends task definitions to support additional command-line arguments
src/tree/localProject/LocalProjectTreeItem.ts	Updates event handlers to use new event object pattern
src/commands/pickFuncProcess.ts	Returns terminal stream in API response for external consumers
src/extension.ts	Registers the new debug view and disposes terminal event reader on deactivation
package.json	Defines view contribution, commands, menus, and new setting
package.nls.json	Adds localized strings for the new feature
extension.bundle.ts	Exports new utility functions for external use
test/funcHostErrorContext.test.ts	Tests for error detection and context extraction
test/ansiUtils.test.ts	Tests for ANSI control character stripping

src/debug/FunctionHostDebugView.ts

Copilot · 2026-01-14T23:34:01Z

src/funcCoreTools/funcHostTask.ts

+    terminalEventReader = vscode.window.onDidStartTerminalShellExecution(async (terminalShellExecEvent) => {
+        /**
+         * This will pick up any terminal that, including those started outside of tasks (e.g. via the command palette).
+         * But we don't actually access the terminal stream until the `func host start` task starts, at which time this will be pointing to the correct terminal
+         * */
+        latestTerminalShellExecutionEvent = terminalShellExecEvent;


The terminal shell execution event listener is registered before func host task starts and stores the latest event in a global variable. This creates a race condition: if multiple terminals are opened or if a non-func terminal is opened just before the func task starts, latestTerminalShellExecutionEvent could point to the wrong terminal. Consider matching terminals more precisely by correlating the task execution with the terminal, or by checking if the terminal's command matches the func host start pattern when consuming the stream.

The main issue here is that onDidStartTerminalShellExecution always fires before onDidStartTask so if I register within onDidStartTask, it'll be too late.

The other issue is that for whatever reason, the TerminalShellExecution doesn't properly display custom tasks so I can't even determine if it's a function task by commandLine. If I look at the terminal, since it fires before the terminal UI actually updates, the terminal name is incorrect.

@copilot open a new pull request to apply changes based on this feedback

Curious to see what it comes up with.

src/commands/pickFuncProcess.ts

src/utils/copilotChat.ts

Copilot · 2026-01-14T23:34:02Z

src/debug/registerFunctionHostDebugView.ts

+export function registerFunctionHostDebugView(context: vscode.ExtensionContext): void {
+    const provider = new FuncHostDebugViewProvider();
+
+    context.subscriptions.push(
+        vscode.window.registerTreeDataProvider(viewId, provider),
+        onRunningFuncTasksChanged(() => {
+            provider.refresh();
+            void tryOpenDebugViewOnFirstFuncHostError();
+        }),
+    );
+
+    // Ensure the context key is correct on activation.
+    void refreshFuncHostDebugContext();
+
+    registerCommand('azureFunctions.funcHostDebug.clearErrors', async (actionContext: IActionContext) => {
+        actionContext.telemetry.properties.source = 'funcHostDebugView';
+        for (const folder of vscode.workspace.workspaceFolders ?? []) {
+            for (const t of runningFuncTaskMap.getAll(folder)) {
+                if (!t) {
+                    continue;
+                }
+
+                if ((t.errorLogs?.length ?? 0) > 0) {
+                    t.errorLogs = [];
+                }
+            }
+        }
+
+        provider.refresh();
+    });
+
+    registerCommand('azureFunctions.funcHostDebug.copyRecentLogs', async (actionContext: IActionContext, args: unknown) => {
+        actionContext.telemetry.properties.source = 'funcHostDebugView';
+        if (!isHostTaskNode(args)) {
+            return;
+        }
+
+        const task = runningFuncTaskMap.get(args.workspaceFolder, args.cwd);
+        const text = getRecentLogsPlainText(task);
+        await vscode.env.clipboard.writeText(text);
+    });
+
+    registerCommand('azureFunctions.funcHostDebug.showRecentLogs', async (actionContext: IActionContext, args: unknown) => {
+        actionContext.telemetry.properties.source = 'funcHostDebugView';
+        if (!isHostTaskNode(args)) {
+            return;
+        }
+
+        const task = runningFuncTaskMap.get(args.workspaceFolder, args.cwd);
+        const text = getRecentLogsPlainText(task);
+
+        const doc = await vscode.workspace.openTextDocument({
+            content: text || localize('funcHostDebug.noLogs', 'No logs captured yet.'),
+            language: 'log',
+        });
+        await vscode.window.showTextDocument(doc, { preview: true });
+    });
+
+    registerCommand('azureFunctions.funcHostDebug.askCopilot', async (actionContext: IActionContext, args: unknown) => {
+        actionContext.telemetry.properties.source = 'funcHostDebugView';
+        if (!isHostErrorNode(args)) {
+            return;
+        }
+
+        // Use the exact message shown in the error node tooltip.
+        const errorContext = stripAnsiControlCharacters(args.message).trim() || args.message;
+
+        const scopeLabel = typeof args.workspaceFolder === 'object'
+            ? args.workspaceFolder.name
+            : localize('funcHostDebug.globalScope', 'Global');
+
+        const prompt = [
+            'I am debugging an Azure Functions project locally in VS Code.',
+            `Function Host Port: ${args.portNumber}`,
+            `Workspace: ${scopeLabel}`,
+            args.cwd ? `CWD: ${args.cwd}` : undefined,
+            '',
+            'The Functions host produced an error. Diagnose the likely cause and suggest concrete next steps to fix it.',
+            '',
+            'Error output:',
+            errorContext,
+        ].filter((l): l is string => Boolean(l)).join('\n');
+
+        await openCopilotChat(prompt);
+    });
+
+    registerCommand('azureFunctions.funcHostDebug.refresh', async (actionContext: IActionContext) => {
+        actionContext.telemetry.properties.source = 'funcHostDebugView';
+        provider.refresh();
+        await refreshFuncHostDebugContext();
+    });
+}


The new FuncHostDebugViewProvider class and registerFunctionHostDebugView function lack test coverage. Given that other components in the repository have comprehensive test coverage (as seen in the test directory), these new components should also have tests covering tree item creation, command handlers, error node generation, and the refresh logic.

@copilot open a new pull request to apply changes based on this feedback

Copilot · 2026-01-14T23:34:04Z

src/utils/copilotChat.ts

+export async function openCopilotChat(prompt: string): Promise<void> {
+    const trimmed = (prompt ?? '').trim();
+    if (!trimmed) {
+        return;
+    }
+
+    const candidates: Array<{ command: string; args: unknown[] }> = [
+        // Newer VS Code variants
+        { command: 'workbench.action.chat.open', args: [trimmed] },
+        { command: 'workbench.action.chat.open', args: [{ query: trimmed }] },
+        // Older / alternate variants
+        { command: 'workbench.action.openChat', args: [trimmed] },
+        // Copilot extensions (IDs vary by version)
+        { command: 'github.copilot.openChat', args: [trimmed] },
+        { command: 'github.copilot-chat.openChat', args: [trimmed] },
+    ];
+
+    for (const { command, args } of candidates) {
+        try {
+            await vscode.commands.executeCommand(command, ...args);
+            return;
+        } catch {
+            // Ignore and try the next candidate
+        }
+    }
+
+    void vscode.window.showWarningMessage(localize(
+        'funcHostDebug.copilotChatUnavailable',
+        'Unable to open Copilot Chat. Please ensure GitHub Copilot Chat is installed and enabled.'
+    ));
+}


The openCopilotChat function lacks test coverage. This function attempts multiple command variants and should be tested to verify it tries all fallbacks and shows the appropriate warning message when all attempts fail.

src/funcCoreTools/funcHostTask.ts

src/funcCoreTools/funcHostErrorUtils.ts

src/funcCoreTools/funcHostTask.ts

Copilot · 2026-01-14T23:34:05Z

src/funcCoreTools/funcHostErrorUtils.ts

+const redAnsiRegex = /\u001b\[(?:[0-9;]*31m|[0-9;]*91m|38;5;(9|1)m)/;
+
+export function isFuncHostErrorLog(log: string): boolean {
+    return redAnsiRegex.test(log);


The isFuncHostErrorLog function only checks for red ANSI codes, but error logs might not always be colored red (depending on the terminal configuration or the Functions runtime version). Consider adding fallback detection for common error patterns like lines starting with "Error:", "[Error]", "Exception:", etc., to make error detection more robust across different environments.

Suggested change

return redAnsiRegex.test(log);

// First, prefer detection based on red ANSI color codes (backwards compatible behavior).

if (redAnsiRegex.test(log)) {

return true;

}

// Fallback: detect common error patterns in the plain-text log line (no ANSI/control chars).

const plain = stripAnsiControlCharacters(log).trim();

if (!plain) {

return false;

}

const lower = plain.toLowerCase();

// Typical error prefixes from Functions host logs and similar environments.

if (lower.startsWith('error:') || lower.startsWith('[error]') || lower.startsWith('exception:')) {

return true;

}

return false;

Copilot · 2026-01-15T00:01:48Z

@nturinski I've opened a new pull request, #4885, to work on those changes. Once the pull request is ready, I'll request review from you.

Copilot · 2026-01-15T00:03:35Z

@nturinski I've opened a new pull request, #4886, to work on those changes. Once the pull request is ready, I'll request review from you.

Co-authored-by: Copilot <[email protected]>

Copilot · 2026-01-15T00:05:27Z

@nturinski I've opened a new pull request, #4887, to work on those changes. Once the pull request is ready, I'll request review from you.

…4885) * Initial plan * Add JSDoc documentation for IStartFuncProcessResult interface Co-authored-by: nturinski <[email protected]> --------- Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: nturinski <[email protected]>

* Initial plan * Add AbortController to prevent infinite stream iteration Co-authored-by: nturinski <[email protected]> --------- Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: nturinski <[email protected]>

Copilot · 2026-01-15T00:21:52Z

@nturinski I've opened a new pull request, #4888, to work on those changes. Once the pull request is ready, I'll request review from you.

Co-authored-by: Copilot <[email protected]>

Removed exhaustive check for FuncHostDebugNode.

bwateratmsft · 2026-01-16T18:54:48Z

src/debug/FuncTaskProvider.ts

        const funcCliPath = await getFuncCliPath(context, folder);
+        const args = (definition?.args || []) as string[];
+        if (args.length > 0) {
+            command = `${command} ${args.join(' ')}`;


Since the VSCode Task API accepts argument lists, why not use that?

bwateratmsft · 2026-01-16T18:58:23Z

src/utils/copilotChat.ts

+    const candidates: Array<{ command: string; args: unknown[] }> = [
+        // Newer VS Code variants
+        { command: 'workbench.action.chat.open', args: [trimmed] },
+        { command: 'workbench.action.chat.open', args: [{ query: trimmed }] },
+        // Older / alternate variants
+        { command: 'workbench.action.openChat', args: [trimmed] },
+        // Copilot extensions (IDs vary by version)
+        { command: 'github.copilot.openChat', args: [trimmed] },
+        { command: 'github.copilot-chat.openChat', args: [trimmed] },
+    ];


Does the minimum VSCode version we have in this extension exclude any of these?

MicroFish91 · 2026-01-22T23:22:06Z

Very cool, I have it as a todo to review this either tomorrow or early next week!

MicroFish91 · 2026-01-28T00:55:06Z

src/funcCoreTools/funcHostTask.ts

+    return tasks;
+}
+
+async function updateFuncHostDebugContext(): Promise<void> {


I'm running into an issue on error where the Function Host Debug view is not showing up. Well, at least that's what it appeared like initially. In reality, after I set some breakpoints, I realized that it actually is getting shown, but then immediately gets hidden.

I think for some reason this update function is called to show the view, and then for some reason gets called again and causes the view to hide.

My repro steps were: (1) create a DTS project via createNewProject, (2) hit F5, and (3) answer skip for now so nothing gets set for both connections. This causes this func CLI error which I was expecting to show up:

I should be in office tomorrow so if you're not able to repro maybe we can investigate on my machine, lmk!

nturinski and others added 30 commits October 24, 2025 10:55

Implementation for debug-isolated flag and streaming func CLI output

6e5b61c

Update src/utils/stream.ts

e9c255d

Co-authored-by: Copilot <[email protected]>

Address copilot feedback

067e04d

Merge branch 'nat/fileBasedPickProcess' of https://github.com/microso…

d046ac9

…ft/vscode-azurefunctions into nat/fileBasedPickProcess

Refactor to set up stream in funcHostTasks

606f130

Delete test snippet

44e8382

Add headerto stream file

9726543

Remove the done call

d4f3b56

Update src/debug/FuncTaskProvider.ts

c7618c7

Co-authored-by: Copilot <[email protected]>

WIP waiting for VSCode insiders fix

b8dd0bf

Use onDidStartTerminalShellExecution API instead of proposed

d673a73

Remove proposed files

2dfd68d

Merge branch 'nat/fileBasedPickProcess' of https://github.com/microso…

5035c9a

…ft/vscode-azurefunctions into nat/fileBasedPickProcess

Add note

8a751c8

Remove unused async moniker

e5adbb9

Whoops, wrong async

6454ca8

Little bit of cleaning

544cd45

Remove unusued function helper

52780f7

Last commit, I swears it

3dc0fc5

Move event handler, added note

e36604c

Rename function due to PR feedback

5bfbb42

Merge branch 'main' of https://github.com/microsoft/vscode-azurefunct…

a9c1f08

…ions into nat/fileBasedPickProcess

Merge branch 'nat/fileBasedPickProcess' of https://github.com/microso…

e1ee414

…ft/vscode-azurefunctions into nat/fileBasedPickProcess

Push up WIP

bc365fa

Push up WIP

5d5b38f

Merge branch 'nat/fileBasedPickProcess' of https://github.com/microso…

192b107

…ft/vscode-azurefunctions into nat/fileBasedPickProcess

WIP for postDebug copilot analysis

577a57d

Add debug command activity

e8b519d

WIP for copilot postdebug

e0e5c03

Merge branch 'main' of https://github.com/microsoft/vscode-azurefunct…

8786288

…ions into nat/fileBasedPickProcess

Nathan Turinski added 7 commits January 7, 2026 15:47

Merge with main

adc4bc4

Fix linter

df16af2

MVP for func debugger view

8707910

Setting for debugger view, show first error

6dff88e

Refactoring/cleaning up

412b751

Remove the stop action and implement clear errors

8fae446

Clean up some code

9e897af

nturinski requested a review from a team as a code owner January 14, 2026 22:56

nturinski requested a review from Copilot January 14, 2026 23:29

Copilot started reviewing on behalf of nturinski January 14, 2026 23:29 View session

Copilot AI reviewed Jan 14, 2026

View reviewed changes

Remove the terminal dispose since it is not reinstantiated later

d30fda1

Copilot AI mentioned this pull request Jan 15, 2026

Add JSDoc documentation for IStartFuncProcessResult stream property #4885

Merged

Copilot AI mentioned this pull request Jan 15, 2026

Add test coverage for FuncHostDebugViewProvider #4886

Draft

nturinski and others added 2 commits January 14, 2026 16:03

Update src/funcCoreTools/funcHostTask.ts

759fb6a

Co-authored-by: Copilot <[email protected]>

Update src/funcCoreTools/funcHostErrorUtils.ts

8ac0664

Co-authored-by: Copilot <[email protected]>

Copilot AI mentioned this pull request Jan 15, 2026

Prevent infinite stream iteration when func host task terminates #4887

Merged

Copilot AI and others added 2 commits January 14, 2026 16:15

Copilot AI mentioned this pull request Jan 15, 2026

Fix race condition in terminal event handling by filtering func host events #4888

Draft

nturinski and others added 2 commits January 14, 2026 16:35

Update src/debug/FunctionHostDebugView.ts

24d396e

Co-authored-by: Copilot <[email protected]>

Remove exhaustive check from switch statement

2ebf2b6

Removed exhaustive check for FuncHostDebugNode.

bwateratmsft reviewed Jan 16, 2026

View reviewed changes

MicroFish91 reviewed Jan 28, 2026

View reviewed changes

-    return redAnsiRegex.test(log);
+    // First, prefer detection based on red ANSI color codes (backwards compatible behavior).
+    if (redAnsiRegex.test(log)) {
+        return true;
+    }
+    // Fallback: detect common error patterns in the plain-text log line (no ANSI/control chars).
+    const plain = stripAnsiControlCharacters(log).trim();
+    if (!plain) {
+        return false;
+    }
+    const lower = plain.toLowerCase();
+    // Typical error prefixes from Functions host logs and similar environments.
+    if (lower.startsWith('error:') || lower.startsWith('[error]') || lower.startsWith('exception:')) {
+        return true;
+    }
+    return false;

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