Trace Debugger

Debug and analyze AILANG operations using OpenTelemetry distributed tracing. This skill helps identify performance bottlenecks, understand code flow, and debug issues using trace data from GCP Cloud Trace.

Quick Start

Most common usage:

# User says: "Why is compilation slow?"
# This skill will:
# 1. Check telemetry is configured
# 2. Run the slow operation with tracing
# 3. Query recent traces with ailang trace list
# 4. Analyze timing breakdown per phase
# 5. Identify the bottleneck

# Check telemetry status
ailang trace status

# List recent traces
ailang trace list --hours 2 --limit 20

# View specific trace hierarchy
ailang trace view <trace-id>

When to Use This Skill

Invoke this skill when:

• User asks to debug slow compilation or type checking
• User wants to analyze benchmark performance
• User mentions "bottleneck", "slow", "hang", or "performance"
• User wants to understand execution flow across components
• User asks "why is X taking so long?"
• User needs to compare timing between runs

Telemetry Prerequisites

Before debugging with traces:

# Option 1: Google Cloud Trace (recommended)
export GOOGLE_CLOUD_PROJECT=your-project-id

# Option 2: Local Jaeger
docker run -d -p 16686:16686 -p 4318:4318 jaegertracing/all-in-one
export OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:4318

# Option 3: AILANG Observatory Dashboard (local UI)
ailang server  # Starts server on localhost:1957
# View traces at http://localhost:1957 → Observatory tab

# Verify configuration
ailang trace status

Observatory Dashboard Setup (v0.6.3+)

The Observatory provides a local dashboard for viewing traces from Claude Code, Gemini CLI, and AILANG.

Start the Server

ailang server
# Or: make services-start

Configure Claude Code

Add to ~/.claude/settings.json:

{
  "env": {
    "CLAUDE_CODE_ENABLE_TELEMETRY": "1",
    "OTEL_LOGS_EXPORTER": "otlp",
    "OTEL_METRICS_EXPORTER": "otlp",
    "OTEL_EXPORTER_OTLP_PROTOCOL": "http/json",
    "OTEL_EXPORTER_OTLP_ENDPOINT": "http://localhost:1957",
    "OTEL_RESOURCE_ATTRIBUTES": "ailang.source=user"
  }
}

What Claude Code sends: Events via OTLP logs (token counts, costs, model, session info)

Configure Gemini CLI

Add to ~/.gemini/settings.json:

{
  "telemetry": {
    "enabled": true
  }
}

And add to shell profile (~/.zshenv, ~/.bashrc):

export GEMINI_TELEMETRY_ENABLED=true
export OTEL_EXPORTER_OTLP_ENDPOINT=http://localhost:1957
export OTEL_EXPORTER_OTLP_PROTOCOL=http/json
export OTEL_RESOURCE_ATTRIBUTES="ailang.source=user"

What Gemini CLI sends: Full traces (complete span hierarchy)

Environment Variables Reference

Variable	Purpose	Example
CLAUDE_CODE_ENABLE_TELEMETRY	Enable Claude Code telemetry	1
OTEL_LOGS_EXPORTER	Log export protocol	otlp
OTEL_METRICS_EXPORTER	Metrics export protocol	otlp
OTEL_EXPORTER_OTLP_PROTOCOL	Transport protocol	http/json
OTEL_EXPORTER_OTLP_ENDPOINT	Observatory URL	http://localhost:1957
OTEL_RESOURCE_ATTRIBUTES	Span metadata	ailang.source=user
GEMINI_TELEMETRY_ENABLED	Enable Gemini CLI telemetry	true

OTLP Endpoints

The Observatory receives data on:

• /v1/traces - Trace spans (Gemini CLI, AILANG)
• /v1/logs - Log records (Claude Code events)
• /v1/metrics - Metrics data

Both protobuf and JSON formats are supported.

Verify Telemetry is Working

1. Ensure ailang server is running
2. Run a Claude Code or Gemini CLI command
3. Open http://localhost:1957 → Observatory tab
4. New traces should appear automatically

Note: If server is not running, OTLP exports fail silently (no impact on CLI tools).

Available Scripts

scripts/check_traces.sh [hours] [filter]

Quick check for recent traces with optional filtering.

Usage:

# Check last hour of traces
.claude/skills/trace-debugger/scripts/check_traces.sh

# Check last 4 hours, filter by eval
.claude/skills/trace-debugger/scripts/check_traces.sh 4 "eval.suite"

# Check compilation traces
.claude/skills/trace-debugger/scripts/check_traces.sh 1 "compile"

scripts/analyze_compilation.sh <file.ail>

Run a file with tracing and analyze compilation phases.

Usage:

# Analyze compilation timing
.claude/skills/trace-debugger/scripts/analyze_compilation.sh examples/runnable/factorial.ail

Workflow

1. Verify Telemetry Configuration

ailang trace status

Expected output shows either GCP or OTLP mode enabled. If disabled, set environment variables.

2. Reproduce the Issue with Tracing

Run the operation that's slow/problematic:

# For compilation issues
GOOGLE_CLOUD_PROJECT=your-project ailang run --caps IO --entry main file.ail

# For eval issues
GOOGLE_CLOUD_PROJECT=your-project ailang eval-suite --models gpt5-mini --benchmarks simple_hello

# For message system issues
GOOGLE_CLOUD_PROJECT=your-project ailang messages list

3. Query Recent Traces

# List recent traces
ailang trace list --hours 1 --limit 10

# Filter by operation type
ailang trace list --filter "compile"
ailang trace list --filter "eval.suite"
ailang trace list --filter "messages"

4. Analyze Trace Hierarchy

# Get full trace details
ailang trace view <trace-id>

Look for:

• Deep nesting: Indicates recursive operations
• Long durations: Shows bottlenecks
• Missing child spans: May indicate early exit or error
• Parallel spans: Shows concurrent operations

5. Interpret Results

Compiler Pipeline Spans:

Span	What to Look For
compile.parse	Long = complex syntax, large file
compile.elaborate	Long = many surface→core transforms
compile.typecheck	Long = complex type inference, possible hang
compile.validate	Long = many nodes to validate
compile.lower	Long = complex operator lowering

Eval Harness Spans:

Span	What to Look For
eval.suite	Total benchmark run time
eval.benchmark	Individual benchmark, check benchmark.success
*.generate	AI API call time (openai, anthropic, gemini)

Messaging Spans:

Span	What to Look For
messages.send	Message creation time
messages.list	Query time, check list.result_count
messages.search	Semantic search time

Instrumented Components

Current trace coverage in AILANG:

✅ Fully Instrumented

• Compiler Pipeline (compile.*) - All 6 phases traced
• Eval Harness (eval.suite, eval.benchmark) - Suite and per-benchmark
• Messaging (messages.*) - Send, list, read, search
• AI Providers (anthropic.generate, openai.generate, gemini.generate, ollama.generate)
• Server (HTTP middleware) - Request/response tracing
• Coordinator (coordinator.execute_task) - Task lifecycle

🔜 Prioritized Future Instrumentation

Based on analysis of 280+ implemented design docs and actual bug patterns:

Priority	Component	Spans	Debug Value
P1	Type System	types.unify, types.substitute	4+ hours saved per cyclic type/metadata bug
P2	Module Resolution	modules.resolve, modules.load	1-2 hours saved per import error
P3	Codegen	codegen.type_lookup, codegen.record	Catch fallbacks before Go compile
P4	Pattern Matching	match.compile, match.coverage	Rare but complex debugging

See resources/trace_patterns.md for detailed span definitions and implementation patterns.

Resources

Trace Patterns Reference

See `resources/trace_patterns.md` for:

• Common debugging patterns
• Trace attribute reference
• Performance baseline expectations

Span Reference

See docs/docs/guides/telemetry.md for:

• Complete span list with attributes
• Environment variable configuration
• Architecture diagrams

Progressive Disclosure

This skill loads information progressively:

1. Always loaded: This SKILL.md file (workflow overview)
2. Execute as needed: Scripts in scripts/ directory
3. Load on demand: resources/trace_patterns.md (detailed patterns)

Notes

• Traces require telemetry environment variables set
• GCP traces may take 30-60 seconds to appear in console
• Local Jaeger provides instant visibility
• Zero overhead when telemetry is disabled
• Use --json flag for programmatic trace analysis

Proactive Trace Improvement

When debugging with traces, actively look for opportunities to add more instrumentation!

If you encounter:

• A debugging session where traces didn't help identify the issue
• A component that would benefit from finer-grained spans
• Missing attributes that would have been useful

Suggest adding traces by:

1. Noting the component and what information would help
2. Proposing span name and attributes (see resources/trace_patterns.md)
3. Creating a design doc for significant additions

Example suggestion format:

Debugging [X] was difficult because traces didn't show [Y].

Suggested addition:
- Span: `component.operation`
- Attributes: `input`, `output`, `duration_ms`
- Location: `internal/package/file.go`
- Debug value: Would show [specific insight]

This helps continuously improve AILANG's observability based on real debugging needs.

Tracing Scope Limitation

Traces only cover AILANG tooling, NOT generated Go code!

What IS Traced	What is NOT Traced
ailang compile phases	Generated Go binary execution
ailang run (AILANG interpreter)	Go code after go build
ailang eval-suite benchmarks	The actual AI-generated code running
ailang messages operations	User application runtime

To debug generated Go code:

• Use Go's standard profiling (go tool pprof)
• Add your own tracing in generated code templates
• Use DEBUG_CODEGEN=1 to see what code is generated
• Add log.Printf to internal/codegen/templates/ if needed

Future possibility: Generate OTEL spans INTO Go code for runtime tracing (not implemented)