Add inline file/URL reference syntax (@./path, @../path, @url) with path security validation #8880

Copilot · 2026-01-04T13:59:38Z

Adds inline syntax for embedding file and URL content in workflow prompts at runtime. The @ syntax is pure syntactic sugar that converts to {{#runtime-import}} macros, with both files and URLs processed through a unified code path.

Security Features:

File paths must start with ./ or ../ (relative paths only)
All paths are normalized and validated to ensure they stay within the git repository root
Attempts to escape the git root are rejected with security errors

Syntax

Three new patterns processed during prompt interpolation:

@./path/to/file or @../path/to/file - Inline entire file content (relative paths required)
@./path/to/file:10-20 - Inline specific line range (1-indexed, inclusive)
@https://example.com/file.txt - Fetch and inline URL content (cached 1 hour)

---
on: pull_request
engine: copilot
---

# Code Review

Follow standards:
@./docs/coding-standards.md

Review this function:
@./src/auth.go:45-75

Use security checklist:
@https://raw.githubusercontent.com/org/security/main/checklist.md

Important: @path without ./ or ../ prefix will NOT be processed and stays as plain text.

Implementation

Unified Runtime Import System (runtime_import.cjs)

convertInlinesToMacros() - Converts @./path, @../path, and @url syntax to {{#runtime-import}} macros
Path pattern: /@(\.\.?\/[a-zA-Z0-9_\-./]+)(?::(\d+)-(\d+))?/g ensures explicit relative paths only
processRuntimeImport() - Now async, handles both files and URLs with optional line range parameters
- Path Security: Normalizes paths using path.normalize() and validates they stay within git root
- Uses path.relative() to detect attempts to escape workspace directory
- Rejects paths where relative path starts with .. or is absolute
processUrlImport() - HTTP/HTTPS fetch with SHA256-keyed cache, 1-hour TTL
Email address filtering via character lookahead (skips [email protected])
Single unified code path for all content importing (no duplication)

Integration (interpolate_prompt.cjs)

Step 1: Convert @./path, @../path, and @url to {{#runtime-import}} macros
Step 2: Process all runtime-import macros (files and URLs together)
Step 3: Variable interpolation
Step 4: Template conditionals

Processing Flow:

@./path → {{#runtime-import ./path}} ┐
@../path → {{#runtime-import ../path}} ├→ processRuntimeImports() → processRuntimeImport()
@url → {{#runtime-import url}}        ┘                                    ↓
                                                              [Path Security Validation]
                                                                           ↓
                                                                  [File/URL Content]

Key Features:

✅ {{#runtime-import}} supports both files and URLs
✅ Line ranges work for both: {{#runtime-import ./path:10-20}} and {{#runtime-import https://url:10-20}}
✅ @ is pure syntactic sugar - converts to macros before processing
✅ File paths must start with ./ or ../ for security
✅ Paths without ./ or ../ are ignored (stay as plain text)
✅ Path normalization and validation ensures paths stay within git root
✅ Security checks prevent directory traversal attacks
✅ Single code path eliminates duplication
✅ Maintains existing sanitization (front matter removal, XML comments, ${{}} macro detection)

Security Validation

All file paths undergo comprehensive security validation:

Path Normalization: Uses path.normalize() to resolve . and .. components
Boundary Validation: Uses path.relative() to verify resolved path stays within workspace
Escape Detection: Rejects paths where relative path starts with .. or is absolute
Clear Error Messages: Security violations include path and git root context

Example Security Scenarios:

✅ Allowed (within git root):

@./docs/file.md - Simple relative path
@./a/b/../../c/file.txt - Resolves to ./c/file.txt within git root
@./subdir/../file.txt - Resolves to ./file.txt within git root

❌ Rejected (escapes git root):

@../../../etc/passwd - Security error: escapes git root
@./../../outside/file.txt - Security error: resolves outside workspace

Tests

84 tests in runtime_import.test.cjs covering all syntax variants, edge cases, error paths, and security scenarios
Added 6 security tests verifying path validation (escape prevention and valid nested paths)
Added tests verifying @path (without ./) is NOT processed
Added tests for @../path syntax
All tests updated to handle async processing
2360 total JS tests pass
Go unit tests pass (no regressions)

Documentation

docs/file-url-inlining.md - Syntax reference, examples, error handling, security validation
examples/file-url-inlining-demo.md - Working demo workflow
specs/file-inlining.md - Architecture, use cases, security considerations

Original prompt

Add support for file/url inlining syntax in prompt text.

@path
@url (cached)
@path:startline-endline (starting line index at 1)

This functionality is similar to the existing "runtime-import" feature and should reuse the same implementation.

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.

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

pelikhan · 2026-01-04T14:15:35Z

@copilot convert file inlines into runtime-import macro then apply runtime-import importer JavaScript. Do not duplicate inlining code.

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

pelikhan · 2026-01-04T14:26:06Z

@copilot convert file inlines into runtime-import macro then apply runtime-import importer JavaScript. Do not duplicate inlining code

… macros - Convert @path and @path:line-line to {{#runtime-import}} macros instead of duplicating code - Add line range support to processRuntimeImport() function - Remove duplicate processFileInline() and processFileInlines() functions - Update interpolate_prompt.cjs to convert @path before processing runtime imports - Update tests to reflect new architecture (75 tests passing) Co-authored-by: pelikhan <[email protected]>

Copilot · 2026-01-04T14:38:34Z

@copilot convert file inlines into runtime-import macro then apply runtime-import importer JavaScript. Do not duplicate inlining code.

Refactored to convert @path syntax to {{#runtime-import}} macros instead of duplicating code. The implementation now:

Converts @path and @path:line-line to {{#runtime-import path}} and {{#runtime-import path:line-line}} macros
Extended processRuntimeImport() to handle line range parameters
Removed duplicate processFileInline() and processFileInlines() functions
Processing flow: convert @path → process runtime-import macros → process URLs → interpolate variables → render templates

This eliminates code duplication and reuses the existing runtime-import infrastructure for all file processing. All 75 tests pass.

Commit: d6051c0

Copilot · 2026-01-04T14:42:13Z

@copilot convert file inlines into runtime-import macro then apply runtime-import importer JavaScript. Do not duplicate inlining code

Already completed in commit d6051c0. The implementation converts @path syntax to {{#runtime-import}} macros and reuses the existing runtime-import code (no duplication). All 75 tests passing.

pelikhan · 2026-01-04T14:45:26Z

@copilot add support for line range and URLs in runtime-import then use same code path. @ is just a syntactic sugar

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

pelikhan · 2026-01-04T15:29:27Z

@copilot keep working

@url

- Extended processRuntimeImport() to detect and handle URLs (https:// and http://) - Added processUrlImport() for URL fetching with caching (reuses existing fetchUrlContent) - Made processRuntimeImports() async to handle URL imports - Updated convertInlinesToMacros() to convert both @path and @url to {{#runtime-import}} - Removed separate processUrlInlines() path - URLs now go through same code as files - Updated interpolate_prompt.cjs to use single unified path for all imports - Updated all tests to be async and added URL conversion tests - All 75 tests passing @ syntax is now pure syntactic sugar that converts to {{#runtime-import}} macros Co-authored-by: pelikhan <[email protected]>

Copilot · 2026-01-04T15:39:44Z

@copilot keep working

Completed the refactoring. @ is now pure syntactic sugar:

✅ {{#runtime-import}} supports both files and URLs
✅ Line ranges work for both: {{#runtime-import path:10-20}} and {{#runtime-import https://url:10-20}}
✅ @path and @url convert to {{#runtime-import}} macros
✅ Single unified code path - no duplication

URLs are now processed through the same runtime-import infrastructure as files. All 75 tests passing.

Commit: 6483398

pelikhan

@copilot @ syntax only supports local file paths starting with ./ or ../ as long as the resolved path is within the git root.

@path should be ignored
@./path should be processed

pelikhan · 2026-01-04T15:42:26Z

specs/file-inlining.md

@@ -0,0 +1,326 @@
+# File/URL Inlining Feature Implementation Summary


@copilot move to specs/file-inlining.me

Moved IMPLEMENTATION_SUMMARY.md to specs/file-inlining.md.

Commit: 2e9c5fd

pelikhan · 2026-01-04T16:00:28Z

@copilot ensure that the resolve path is cleaned and in the git root

pelikhan · 2026-01-04T16:05:07Z

@copilot make sure path does not contain a nested macro. Refuse { } characters

… root - Added path normalization and validation in processRuntimeImport() - Validates that resolved paths stay within workspace directory (git root) - Uses path.normalize() to clean paths and path.relative() to check boundaries - Rejects paths that escape git root with security error message - Added 6 security tests covering escape attempts and valid nested paths - Updated documentation to explain path security validation - All 84 tests passing Co-authored-by: pelikhan <[email protected]>

Copilot · 2026-01-04T16:06:42Z

@copilot ensure that the resolve path is cleaned and in the git root

Implemented path security validation. All resolved paths are now normalized and validated to stay within git root:

✅ Uses path.normalize() to clean paths and resolve . and .. components
✅ Uses path.relative() to verify resolved path is within workspace
✅ Rejects paths that escape git root with security error
✅ Allows valid nested paths like ./a/b/../../c/file.txt if they resolve within git root

Added 6 security tests. All 84 tests passing.

Commit: 52a3be1

github-actions · 2026-01-04T16:10:59Z

✨ The prophecy is fulfilled... Smoke Codex has completed its mystical journey. The stars align. 🌟

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🎬 THE END — Smoke Claude MISSION: ACCOMPLISHED! The hero saves the day! ✨

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📰 VERDICT: Smoke Copilot has concluded. All systems operational. This is a developing story. 🎤

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📰 DEVELOPING STORY: Smoke Copilot Playwright reports failed. Our correspondents are investigating the incident...

github-actions · 2026-01-04T16:11:02Z

🎉 Yo ho ho! Smoke Copilot Safe Inputs found the treasure and completed successfully! ⚓💰

github-actions · 2026-01-04T16:11:02Z

🤖 DIAGNOSTIC COMPLETE: Smoke Copilot No Firewall STATUS: ALL_UNITS_OPERATIONAL. MISSION_SUCCESS.

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github-actions · 2026-01-04T16:12:56Z

Smoke Test Results

✅ File Writing: Created test file successfully
✅ Bash Tool: Read file back successfully
✅ Safe Input gh Tool: Retrieved merged PRs

Status: PASS - All tests completed successfully

AI generated by Smoke Copilot Safe Inputs

github-actions · 2026-01-04T16:13:06Z

Firewall smoke test

Merged PRs: Fix create_issue test expectations for assignees field; Security: Fix file permissions in copilot_setup.go (alerts [Custom Engine Test] Test Issue Created by Custom Engine #382, [Custom Engine Test] Test Pull Request - Custom Engine Safe Output #381)
Tests: OpenAI curl blocked ✅; GitHub MCP PR fetch ✅; File write/read ✅; Blocked domain curl blocked ✅
Network: SANDBOXED
Overall: PASS

AI generated by Smoke Codex Firewall

github-actions · 2026-01-04T16:13:07Z

Copilot Engine Smoke Test Results

Last 2 Merged PRs:

Fix create_issue test expectations for assignees field #8905: Fix create_issue test expectations for assignees field
[WIP] Fix lint errors in Go code #8904: [WIP] Fix lint errors in Go code

Test Results:

✅ GitHub MCP (default toolsets)
✅ File Writing (/tmp/gh-aw/agent/)
✅ Bash Tools
✅ GitHub MCP Default Toolset (verified get_me not available)
✅ Cache Memory (/tmp/gh-aw/cache-memory/)
✅ Web Fetch
✅ Available Tools

Status: PASS

cc: @pelikhan (PR author/assignee)

AI generated by Smoke Copilot

github-actions · 2026-01-04T16:13:31Z

Smoke Test Results: Copilot Engine (No Firewall) ✅

All smoke tests passed successfully:

✅ Last 2 merged PRs: Fix create_issue test expectations for assignees field #8905 (Fix create_issue test), Security: Fix file permissions in copilot_setup.go (alerts #382, #381) #8903 (Security: Fix file permissions)
✅ Test file created: /tmp/gh-aw/agent/smoke-test-copilot-20695625360.txt
✅ Playwright navigation: Successfully loaded https://github.com (Title: "GitHub · Change is constant. GitHub keeps you ahead. · GitHub")
✅ GitHub CLI via safeinputs-gh: Listed 3 issues (Campaign: File Size Reduction (Project 71) #8901, [refactor] Semantic Function Clustering Analysis - Code Organization Improvements #8896, 📊 Workflow Health Dashboard - 2026-01-04 #8825)

AI generated by Smoke Copilot No Firewall

github-actions · 2026-01-04T16:13:48Z

PR titles reviewed: Fix create_issue test expectations for assignees field; Security: Fix file permissions in copilot_setup.go (alerts #382, #381)
GitHub MCP review ✅
File write/read ✅
Playwright title check ✅
Cache memory write/read ✅
safeinputs-gh gh issues list ❌ (tool not found in PATH)
Status: FAIL

AI generated by Smoke Codex

github-actions · 2026-01-04T16:13:51Z

Smoke Test Results - Claude Engine

Last 2 Merged PRs:

Fix create_issue test expectations for assignees field #8905: Fix create_issue test expectations for assignees field
Format Go code in artifact manager files #8899: Format Go code in artifact manager files

Test Results:
✅ GitHub MCP - Retrieved PRs successfully
✅ File Writing - Created test file in /tmp/gh-aw/agent/
✅ Bash Tool - Verified file creation
✅ Playwright MCP - Navigated to GitHub, title contains "GitHub"
✅ Cache Memory - Created and verified cache file
❌ Safe Input gh Tool - Tool not available in current environment

Overall Status: PASS (5/6 tests)

AI generated by Smoke Claude

Initial plan

8a70b4e

Copilot AI assigned Copilot and pelikhan Jan 4, 2026

Copilot started work on behalf of pelikhan January 4, 2026 14:00 View session

Add file/URL inlining syntax support (@path and @path:line-line)

05a1588

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

Copilot AI and others added 3 commits January 4, 2026 14:18

Add URL inlining support with caching and comprehensive documentation

bafb4b9

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

Add example workflow demonstrating file/URL inlining feature

4b7a9ab

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

Add comprehensive implementation summary and documentation

7a308ce

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

Copilot AI changed the title ~~[WIP] Add support for file/url inlining syntax in prompt text~~ Add inline file/URL reference syntax (@path, @path:line-line, @url) Jan 4, 2026

Copilot finished work on behalf of pelikhan January 4, 2026 14:25

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Changes before error encountered

6bcfbea

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

Copilot started work on behalf of pelikhan January 4, 2026 15:29 View session

Copilot finished work on behalf of pelikhan January 4, 2026 15:40

pelikhan reviewed Jan 4, 2026

View reviewed changes

Copilot started work on behalf of pelikhan January 4, 2026 16:00 View session

Copilot AI changed the title ~~Add inline file/URL reference syntax (@./path, @../path, @url)~~ Add inline file/URL reference syntax (@./path, @../path, @url) with path security validation Jan 4, 2026

Copilot finished work on behalf of pelikhan January 4, 2026 16:07

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pelikhan marked this pull request as ready for review January 4, 2026 16:14

pelikhan merged commit 7f232b8 into main Jan 4, 2026
64 of 67 checks passed

pelikhan deleted the copilot/add-file-url-inline-syntax branch January 4, 2026 16:14

Copilot finished work on behalf of pelikhan January 4, 2026 16:14

		@@ -0,0 +1,326 @@
		# File/URL Inlining Feature Implementation Summary

Add inline file/URL reference syntax (@./path, @../path, @url) with path security validation #8880

Add inline file/URL reference syntax (@./path, @../path, @url) with path security validation #8880

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