feat: Add external folder context for monorepos and full-stack workflows #1693

zamalali · 2025-10-29T12:52:40Z

Problem

@workspace is limited to opened folders. Full-stack and multiple repo developers cannot reference external code (e.g. backend, shared utils) without workspace reloads or manual #file drags.

Solution

Command: github.copilot.chat.addExternalContext QuickPick + folder browse
Hard cap: 3 external folders
Injection: As ChatPromptReference (vscode.prompt.file.external)
Tools: listDir, edit, etc. access external paths via isExternalPath
Exclusions: node_modules, .git, dist, build, .log, .tmp + files.exclude
UX:
- Status bar badge: $(folder) 2/3
- github.copilot.chat.manageExternalContexts remove via QuickPick
- Warnings on cap/exclusion
Env: EXTERNAL_CONTEXT_PATHS (fallback: SYSTEM_CONTEXT_PATHS)

No impact on existing @workspace or open files.

Implementation

ExternalContextService: path management, dedup, cap, events
ExternalContextContribution: commands, UI, badge, filtering
Integrated into chatParticipantRequestHandler, listDirTool, toolUtils

Testing

External paths appear in prompt references
Cap enforced at 3 with warning
Excluded paths skipped + toast
Tools read/write external files
vitest suite: add/cap/remove/events

Limitations

No context chips chat input UI is closed-source in workbench.
→ Status bar + manage command provide full visibility and control.
Max 3 is intentional; future configurability possible.

Ready for review and merge.
All functionality delivered within open-source constraints.

Implement github.copilot.chat.addSystemContext and systemContextService. Add related contributions and i18n updates (package.json, package.nls.json). Add helper tools/utilities used by the feature (listDirTool, toolUtils) and wire into prompt/request handler. Note: To surface this choice in the Copilot Chat 'Add Context' QuickPick, a follow-up UI change is required in the chat/workbench UI.

…rvice Implements github.copilot.chat.addExternalContext command, refactors associated contributions and services, enforces 3-folder cap, and adds dedicated test coverage. Safe sync commit — local testing pending.

…ogic Aligns naming, command wiring, and prompt/tool references with ExternalContext design. Enforces 3-folder cap via IExternalContextService, adds exclusion guardrails and status-bar badge. Includes package and i18n updates.

zamalali · 2025-10-29T12:55:00Z

@microsoft-github-policy-service agree

Copilot

Pull Request Overview

This PR adds external context support to GitHub Copilot Chat, allowing users to add folders outside their workspace that Copilot can access. Users can manage up to 3 external folders via commands and a status bar indicator, with these paths automatically included as chat references.

Key changes:

Implements ExternalContextService to manage external folder paths with events and path comparison logic
Adds UI contribution with commands for adding/managing external folders and a status bar item
Integrates external paths into tool validation (toolUtils, listDirTool) and chat references (chatParticipantRequestHandler)

Reviewed Changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/extension/context/node/externalContextService.ts	Core service managing external paths with events, max limit enforcement, and path comparison logic
src/extension/context/vscode-node/externalContextContribution.ts	UI contribution providing commands, status bar item, and folder picker with exclusion rules
src/extension/context/node/test/externalContextService.spec.ts	Unit tests for external context service covering max paths, events, and removal
src/extension/tools/node/toolUtils.ts	Updates file validation to allow external paths in tools
src/extension/tools/node/listDirTool.tsx	Updates directory listing tool to allow external paths
src/extension/prompt/node/chatParticipantRequestHandler.ts	Injects external paths as chat references for each request
src/extension/extension/vscode-node/services.ts	Registers external context service in DI container
src/extension/extension/vscode-node/contributions.ts	Registers external context contribution
package.nls.json	Adds localization strings for new commands
package.json	Adds command definitions for external context management

Copilot · 2025-10-29T12:57:26Z

src/extension/context/node/externalContextService.ts

+	replaceExternalPaths(paths: readonly URI[]): void {
+		this._paths.clear();
+		for (const path of paths) {
+			this._paths.set(path.toString(), path);


The replaceExternalPaths method does not enforce the MAX_EXTERNAL_PATHS limit, allowing more paths to be set than the maximum. This is inconsistent with addExternalPaths which respects the limit. Add a check to only add paths up to MAX_EXTERNAL_PATHS.

Suggested change

this._paths.set(path.toString(), path);

if (this._paths.size >= MAX_EXTERNAL_PATHS) {

break;

}

const key = path.toString();

if (!this._paths.has(key)) {

this._paths.set(key, path);

}

Copilot · 2025-10-29T12:57:26Z

src/extension/context/node/externalContextService.ts

+		if (potentialParent === child) {
+			return true;
+		}
+


The equality check at lines 115-117 is redundant since the same comparison is already performed by the caller at line 98 (candidateComparable === storedComparable). Remove this check to avoid duplicated logic.

Suggested change

if (potentialParent === child) {

return true;

}

Copilot · 2025-10-29T12:57:27Z

src/extension/prompt/node/chatParticipantRequestHandler.ts

 			this.request = await this.sanitizeVariables();
+			this.turn.request.message = this.request.prompt;
+
+


Extra blank line at line 228 should be removed to maintain consistent spacing according to the project's coding style.

Suggested change

Copilot · 2025-10-29T12:57:27Z

src/extension/prompt/node/chatParticipantRequestHandler.ts

+	private appendExternalContextReferences(): void {
+		const externalUris = this._externalContextService.getExternalPaths();
+		if (!externalUris.length) {
+			return;
+		}
+
+		const existingRefs = this.request.references ?? [];
+
+		const newRefs: ChatPromptReference[] = [];
+		let counter = 0;
+		for (const uri of externalUris) {
+			const alreadyPresent = existingRefs.some(ref => this.matchesReference(ref, uri)) || newRefs.some(ref => this.matchesReference(ref, uri));
+			if (!alreadyPresent) {
+				const id = `${EXTERNAL_CONTEXT_REFERENCE_PREFIX}.${counter++}`;
+				newRefs.push({
+					id,
+					name: uri.fsPath,
+					value: uri,
+					modelDescription: `External context path ${uri.fsPath}`,
+				});
+			}
+		}


The nested loop at line 304 creates O(n*m) complexity checking if URIs are already present. The second check newRefs.some(ref => this.matchesReference(ref, uri)) is unnecessary since newRefs is being built in this loop and cannot contain duplicates from externalUris. Consider using a Set-based approach or remove the redundant newRefs.some() check.

package.json

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

…rnal context reference handling

Copilot

Pull Request Overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Copilot · 2025-10-29T13:37:31Z

src/extension/context/node/externalContextService.ts

+	isExternalPath(uri: URI): boolean {
+		const candidateComparable = this.toComparablePath(uri);
+		for (const stored of this._paths.values()) {
+			const storedComparable = this.toComparablePath(stored);
+
+			if (candidateComparable === storedComparable) {
+				return true;
+			}
+
+			if (this.isSubPath(candidateComparable, storedComparable) || this.isSubPath(storedComparable, candidateComparable)) {
+				return true;
+			}
+		}
+		return false;
+	}


The toComparablePath method is called repeatedly inside the loop, converting the same stored paths on every iteration. Consider caching the comparable paths in a Map alongside the URIs to avoid redundant path normalization operations.

zamalali added 6 commits October 28, 2025 21:44

Merge branch 'microsoft:main' into main

5a42ad1

Merge branch 'microsoft:main' into main

5679597

Merge branch 'main' of https://github.com/zamalali/vscode-copilot-chat

cbf07b4

Copilot AI review requested due to automatic review settings October 29, 2025 12:52

vs-code-engineering bot assigned bhavyaus Oct 29, 2025

vs-code-engineering bot added the triage-needed label Oct 29, 2025

Copilot AI reviewed Oct 29, 2025

View reviewed changes

zamalali and others added 3 commits October 29, 2025 14:18

Update package.json

85aad2c

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

Merge branch 'microsoft:main' into main

74782fb

fix: enforce folder cap, remove redundant checks, and streamline exte…

70de36a

…rnal context reference handling

zamalali requested a review from Copilot October 29, 2025 13:33

Copilot AI reviewed Oct 29, 2025

View reviewed changes

zamalali added 5 commits October 29, 2025 17:41

Merge branch 'microsoft:main' into main

7026caa

Merge branch 'microsoft:main' into main

b4a374a

Merge branch 'main' into main

6f75f9e

Merge branch 'main' into main

c4e4796

Merge branch 'microsoft:main' into main

d84a49f

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zamalali commented Oct 29, 2025 •

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-			this._paths.set(path.toString(), path);
+			if (this._paths.size >= MAX_EXTERNAL_PATHS) {
+				break;
+			}
+			const key = path.toString();
+			if (!this._paths.has(key)) {
+				this._paths.set(key, path);
+			}

		this.request = await this.sanitizeVariables();
		this.turn.request.message = this.request.prompt;

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zamalali commented Oct 29, 2025 •

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