Issue Tracking & Debugging

Load this skill when triaging bug reports, investigating issues, implementing fixes, or writing post-mortem documentation for SWS.

When to load: triaging a new issue report, investigating a regression, writing a fix for a bug, drafting a post-mortem, or reviewing a bug-fix PR.

Issue Triage

Reproducibility First

• Can you reproduce it? Follow the exact steps in the report. If unreproducible, ask the reporter for environment details (OS, architecture, SWS version, config file, TLS setup)
• Minimal reproduction: Reduce the scenario to the smallest config + file structure that triggers the bug. Strip unrelated features
• Write a failing test first: Before fixing, write a test that reproduces the bug. Use the fixture infrastructure in tests/ and src/testing.rs

Severity Classification

Root Cause Analysis

Debugging Process

1. Gather evidence: Logs (-g trace), stack traces, HTTP response headers, request URIs, config file
2. Form a hypothesis: Based on the evidence, propose what might cause the bug
3. Test the hypothesis: Add tracing, run reproduction, or step through with a debugger
4. Identify the root cause: Find the exact line or condition that triggers the bug. Don't stop at symptoms
5. Verify the fix: The reproduction test now passes. The original scenario works

Rust Debugging

• Use tracing crate for structured logs: SWS uses tracing-subscriber. Run with -g trace for maximum detail. Log levels: ERROR (actionable), WARN (unexpected but handled), INFO (key events), DEBUG (detailed), TRACE (noisy)
• Use dbg!() for quick inspection: Temporary, remove before committing
• Enable backtraces: RUST_BACKTRACE=1 for panic backtraces, RUST_LIB_BACKTRACE=1 for error backtraces

HTTP Debugging

• Inspect response headers: Use curl -v http://localhost:8787/path to see full request/response exchange
• Test with specific Accept-Encoding headers: curl -H "Accept-Encoding: br" ... to test compression variant selection
• Check security headers: curl -I http://localhost:8787/ | grep -i 'x-\|strict\|csp\|referrer'
• Test byte-range requests: curl -H "Range: bytes=0-99" http://localhost:8787/file
• CORS preflight debugging: curl -X OPTIONS -H "Origin: https://example.com" -H "Access-Control-Request-Method: GET" http://localhost:8787/
• TLS verification: openssl s_client -connect localhost:8787 -servername localhost

File-Serving Debugging

• Path resolution issues: Check if the file exists at the resolved path. SWS logs the resolved path at trace level
• Hidden file / symlink blocking: Verify --include-hidden and --follow-symlinks settings (both default to false). Hidden files return 404 (stealth), symlinks return 403
• Index file resolution: If a directory returns 404 instead of an index, check --index-files list and file existence
• MIME type issues: SWS uses mime_guess from file extension. If the wrong Content-Type is served, check the file extension

Fix Implementation

Before Writing the Fix

• Is there a failing test that reproduces the bug?
• Is the root cause identified (not just the symptom)?
• Does the fix address the root cause?
• Are there other places in the codebase with the same bug pattern?

Writing the Fix

• Minimal change: Fix the bug with the smallest possible code change. Do not refactor unrelated code in the same PR
• Add a regression test: The reproduction test becomes a permanent regression test
• Update documentation: If the fix changes behavior, update the relevant feature doc in docs/content/features/

Commit Message Format

fix(scope): brief description of the fix

Detailed explanation of the root cause and the fix.
Include steps to reproduce, expected behavior, and actual behavior.

Fixes #123

scope is the affected module or feature (e.g., compression, tls, static-files). See COMMITS.md for the full convention.

Regression Prevention

• The reproduction test stays: Every bug fix adds a test that prevents the same bug from returning
• Check similar code paths: Search the codebase for patterns that could cause the same class of bug
• Add a lint rule if applicable: If a pattern caused the bug and can be detected statically, add a clippy or ESLint rule

Post-Mortem (P0/P1 only)

For critical and high-severity issues, write a brief post-mortem:

1. What happened: Timeline of the incident
2. Root cause: The specific code or configuration that caused it
3. Impact: What users were affected and how
4. Fix: What change resolved the issue
5. Prevention: What process, tooling, or test prevents recurrence

Store post-mortems in docs/post-mortems/YYYY-MM-DD-title.md.

Checklist

• Bug is reproduced and understood
• Root cause identified (not just symptom)
• Failing test written before the fix
• Fix is minimal and addresses root cause
• Regression test added
• Similar code paths checked for the same bug pattern
• Commit message follows format