Improve VS Code extension diagnostics and path handling

[codeprakhar25]

Summary

• Add structured AgentDiff output-channel diagnostics and an AgentDiff: Open Logs command for VS Code Copilot capture.
• Resolve capture state per edited document for multi-root workspaces, repo initialization checks, document versions, and WSL path/process bridging.
• Expand extension tests and README docs around capture limits, debugging, and local test workflow.

Test plan

• git diff --check
• node --test scripts/tests/test_extension.js

Refs #13

[greptile-apps]

Greptile Summary

This PR wires up a structured AgentDiff VS Code output channel with an agentdiff.openLogs command, fixes the Copilot-absent diagnostic flow by registering that command before the Copilot extension guard, adds WSL path/process bridging, and resolves per-document capture state for multi-root workspaces.

• extension.js: openLogsCmd is now registered in context.subscriptions before the Copilot guard, so the diagnostics command works even when Copilot is missing; the save-handler race condition is fixed by deleting the pending entry before awaiting captureDocument; WSL helpers are added for Windows-hosted WSL workspaces.
• test_extension.js (new): Adds an offline test suite covering capture flow, multi-root path scoping, diagnostics, and WSL path translation — but the "Copilot absent" test contains a stale assertion that expects zero subscriptions when there is now one (the openLogsCmd disposable).
• package.json / README.md: Manifest updated with the new command declaration; README clarifies Copilot capture scope, WSL install paths, and how to use the output channel.

Confidence Score: 4/5

Safe to merge after fixing one failing test assertion in the new test suite.

The extension logic itself is sound — registering openLogsCmd before the Copilot guard is the intended fix and works correctly. The new test suite ships with a stale assertion: the Copilot-absent test expects zero subscriptions but one (openLogsCmd) is now always added before the early return, making node --test fail on the changed path.

scripts/tests/test_extension.js — the subscription-count assertion in the Copilot-absent test needs to be updated from 0 to 1.

Important Files Changed

Filename	Overview
scripts/vscode-extension/extension.js	Adds structured output-channel diagnostics, agentdiff.openLogs command (correctly registered before the Copilot guard), WSL path/process bridging, and per-document capture-state tracking. Race condition from save handler is addressed by deleting the pending entry before awaiting captureDocument.
scripts/tests/test_extension.js	New comprehensive test suite. The assertion vscode._subscriptions.length === 0 on the 'Copilot absent' test is now wrong — openLogsCmd is pushed to subscriptions before the early return, making the actual count 1.
scripts/vscode-extension/package.json	Adds the agentdiff.openLogs command declaration to the manifest. Straightforward and correct.
README.md	Minor documentation updates: clarifies Copilot capture scope, notes WSL/remote install path, and adds a paragraph about the AgentDiff output channel and Open Logs command.

Sequence Diagram

sequenceDiagram
    participant VS as VS Code
    participant EXT as extension.js
    participant CH as OutputChannel
    participant GIT as git (execFile)
    participant PY as capture script (spawn)

    VS->>EXT: activate(context)
    EXT->>CH: createOutputChannel('AgentDiff')
    EXT->>VS: registerCommand('agentdiff.openLogs')
    Note over EXT: Copilot guard check
    alt Copilot missing
        EXT->>CH: logEvent warn: inactive_copilot_missing
        EXT-->>VS: return (early exit)
    else Copilot present
        EXT->>VS: register onDidChangeTextDocument
        EXT->>VS: register onDidSaveTextDocument
        EXT->>VS: registerCommand('agentdiff.captureNow')
    end

    VS->>EXT: onDidChangeTextDocument(event)
    EXT->>EXT: buffer lines in pendingChanges[filePath]
    EXT->>EXT: debounce setTimeout(flushAll, FLUSH_DELAY_MS)

    VS->>EXT: onDidSaveTextDocument(doc)
    EXT->>EXT: pendingChanges.delete(filePath)
    EXT->>EXT: cancel timer if no more pending
    EXT->>GIT: rev-parse --show-toplevel / --git-common-dir
    GIT-->>EXT: repoRoot, gitDir
    EXT->>EXT: pathExistsDir(agentdiffDir) initialized?
    alt not initialized
        EXT->>CH: logEvent warn: skipped_repo_not_initialized
    else initialized
        EXT->>PY: spawn capture script (JSON payload via stdin)
    end

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_{Reviews (2): Last reviewed commit: "fix: register openLogs before Copilot gu..." | Re-trigger Greptile}

[greptile-apps]

FLUSH_DELAY_MS can silently become NaN — if AGENTDIFF_EXT_FLUSH_DELAY_MS is set to a non-numeric string (e.g. "off"), Number("off") is NaN. setTimeout(flushAll, NaN) is treated as setTimeout(flushAll, 0) in both browsers and Node.js, causing the debounce window to collapse to zero and every keystroke to trigger an immediate flush.

Suggested change

	const FLUSH_DELAY_MS = Number(process.env.AGENTDIFF_EXT_FLUSH_DELAY_MS || DEFAULT_FLUSH_DELAY_MS);
	const _rawFlushDelay = Number(process.env.AGENTDIFF_EXT_FLUSH_DELAY_MS);
	const FLUSH_DELAY_MS = Number.isFinite(_rawFlushDelay) && _rawFlushDelay > 0 ? _rawFlushDelay : DEFAULT_FLUSH_DELAY_MS;

[github-actions]

AgentDiff Report

Summary

Agent	Lines	%
Prakhar Khatri	579	100%

Review Context

• Intent: unspecified (579 lines, 4 files)
  • Agent/model: Prakhar Khatri / unknown

Files To Review First

File	Lines	Dominant Agent	Intent	Context
scripts/vscode-extension/extension.js	318	Prakhar Khatri	unspecified	trace f583a76c
scripts/tests/test_extension.js	221	Prakhar Khatri	unspecified	trace f583a76c
README.md	36	Prakhar Khatri	unspecified	trace f583a76c
scripts/vscode-extension/package.json	4	Prakhar Khatri	unspecified	trace f583a76c

Trace details

Trace	Agent	Intent	Files	Lines
f583a76c	Prakhar Khatri	unspecified	README.md, scripts/tests/test_extension.js, scripts/vscode-extension/extension.js, scripts/vscode-extension/package.json	566
b500515f	Prakhar Khatri	unspecified	scripts/vscode-extension/extension.js	13

[greptile-apps]

Stale subscription-count assertion will fail

The test asserts vscode._subscriptions.length === 0, but with the new code activate() now calls context.subscriptions.push(openLogsCmd) before the Copilot guard check. When Copilot is absent the function returns early, but the openLogsCmd disposable is already in context.subscriptions, so the length is 1, not 0. Running node --test on this file will produce an AssertionError: 1 == 0 here.

Suggested change

	test('activate returns early without listeners when Copilot is absent', () => {
	const vscode = makeVscodeMock({ copilotInstalled: false });
	activateExt(vscode);
	assert.equal(vscode._subscriptions.length, 0);
	assert.ok(vscode._outputLines.some((line) => line.includes('"event":"extension.inactive_copilot_missing"')));
	});
	assert.equal(vscode._subscriptions.length, 1); // openLogsCmd is registered before the Copilot guard