causetrace

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causetrace is a Python tracing and observability tool for AI coding agents such as Claude Code, Codex CLI, OpenCode, Aider, Continue.dev, and GitHub Copilot. It captures tool calls and links them into causal trees and DAGs, enabling agent debugging, replay, root-cause analysis, and behavior explanation instead of relying on flat timelines.

Data sources: Claude Code (hooks), OpenCode / Continue.dev / GitHub Copilot (log tailing), Codex CLI (rollout parser), Aider (process wrapper) Storage: ~/.causetrace/data/<session_id>.jsonl — append-only JSONL, zero external dependencies

Use Cases

Trace why an AI coding agent made a specific edit or shell call.
Debug Claude Code hooks and Codex CLI rollout sessions from causal context.
Compare agent sessions by topology, transitions, and critical paths.
Collect sanitized runtime traces for agent observability research.

Showcase

The same session viewed four ways — flat vs. causal.

Timeline (flat)

$ causetrace timeline ses_10d2f16e
[03:13:37] Read(file_path=src/main.py)
[03:13:37] Grep(pattern=FIXME)
[03:13:37] Read(file_path=src/utils.py)
[03:13:37] Read(file_path=src/utils.py)
[03:13:38] Edit(file_path=src/utils.py)
[03:13:38] Bash(command=python -m pytest tests/ -x)
[03:13:38] Grep(pattern=counter)
[03:13:38] Edit(file_path=docs/api.md)
[03:13:38] Bash(command=python -m pytest tests/)

Chronological order, but no insight into why each event happened.

Causal Tree

$ causetrace tree ses_10d2f16e
[03:13:37] Read(file_path=src/main.py)
    └─ [03:13:37] Grep(pattern=FIXME)
      └─ [03:13:37] Read(file_path=src/utils.py)
[03:13:37] Read(file_path=src/utils.py)  [caused by: need_context]
    └─ [03:13:38] Edit(file_path=src/utils.py)
      └─ [03:13:38] Bash(command=python -m pytest tests/ -x)
[03:13:38] Grep(pattern=counter)
    └─ [03:13:38] Edit(file_path=docs/api.md)
      └─ [03:13:38] Bash(command=python -m pytest tests/)

Parent→child chains reveal the causal structure: each tool call is a direct response to its parent.

Why (causal chain trace)

$ causetrace why ses_10d2f16e <event_id>
[03:13:38] Grep(pattern=counter) ──→
[03:13:38] Edit(file_path=docs/api.md) ──→
[03:13:38] Bash(command=python -m pytest tests/) ◀── TARGET

Trace why a specific event happened — follow the causal chain backward from any event to its root.

Multi-parent DAG

$ causetrace graph ses_3e23bcc8
[02:42:40] Bash(command=python -m pytest tests/)  ← Edit(file_path=docs/api.md)
[02:42:41] Read(file_path=src/main.py)
[02:42:41] Grep(pattern=FIXME)  ← Read(file_path=src/main.py)
[02:42:41] Read(file_path=src/utils.py)  ← Grep(pattern=FIXME)
[02:42:41] Read(file_path=src/utils.py)
[02:42:41] Edit(file_path=src/utils.py)  ← Read(file_path=src/utils.py)
[02:42:41] Bash(command=python -m pytest tests/ -x)  ← Edit(file_path=src/utils.py)
[02:42:42] Grep(pattern=counter)
[02:42:42] Edit(file_path=docs/api.md)  ← Grep(pattern=counter)

Fan-in DAGs visualize convergent causation — one tool consuming multiple prior results. Support for multi-parent causal links via comma-separated parent_event_id.

Supported Agents

Agent	Method	How it works
Claude Code	Hook bridge	PreToolUse / PostToolUse hooks via `~/.claude/settings.json`
OpenCode	Log tailing	Parses `~/.local/share/opencode/log/*.log` for tool.registry entries
Aider	Process wrapper	Runs `aider` as subprocess, parses stdout for tool calls
Continue.dev	Log tailing	Parses `~/.continue/logs/core.log` for JSON tool call entries
Codex CLI	Rollout parser	Parses `~/.codex/sessions/.../rollout-*.jsonl` — `function_call`/`function_call_output` paired by `call_id`
GitHub Copilot	Log tailing	Parses `~/.config/Code/logs/` extension host logs for Copilot tool calls

# Claude Code — automatic via hooks
causetrace tree <session_id>

# Claude Code — enrich project sessions with reasoning blocks
causetrace enrich-sessions
causetrace enrich <session_id> --save

# OpenCode — enrich DB sessions with reasoning blocks
causetrace enrich-opencode-sessions
causetrace enrich-opencode <session_id> --save

# Codex CLI — enrich rollout sessions with causal chains
causetrace enrich-codex-sessions
causetrace enrich-codex <session_id> --save

# Log-based agents — scan and save (heuristic causality)
causetrace opencode --save
causetrace continue --save
causetrace copilot --save

# Aider — run with tracing
causetrace aider -- --model gpt-4 --yes "fix the bug"

Usage notes:

Claude Code — most precise, captures full causality via Pre/Post hooks
Aider — causetrace aider --save -- [aider args] wraps the CLI; best-effort parsing from output
Codex CLI (enrich) — parses real rollout format: function_call/function_call_output paired by call_id, agent_message for reasoning
OpenCode (enrich) — extracts reasoning + tool calls from SQLite DB with causal parent-child links
Continue.dev, Copilot — post-hoc log scanning; causality inferred from temporal proximity via infer_relations()
Codex CLI (codex) — legacy scanner retained for compatibility; use enrich-codex for validated rollout ingestion
All log-based agents infer causality heuristically — timestamps between events determine parent→child chains

Quick Start

pip install causetrace

# Create a saved sample trace and immediately see the causal tree
causetrace demo

demo prints the generated session ID plus ready-to-run graph, why, and stats commands. No agent configuration or fixture download is required.

Hook up Claude Code

Install recording hooks while preserving existing Claude Code settings:

causetrace install-claude-hook
causetrace doctor

The installer writes ~/.claude/settings.json and creates a settings.json.causetrace.bak backup before its first change. Remove only causetrace hooks with causetrace uninstall-claude-hook.

Scan OpenCode logs

causetrace opencode --save

Parses OpenCode log files, infers causal relations from temporal proximity, and saves as a causetrace session.

Analyze and validate sessions

causetrace validate <session_id>                 # Integrity and malformed JSONL checks
causetrace stats <session_id>                    # Topology summary
causetrace roots <session_id>                    # Local roots and downstream depth
causetrace critical-path <session_id>            # Longest local causal chain
causetrace patterns <session_id> --json          # Structured path/transition/fan-in output
causetrace patterns <session_id> --csv           # Transitions CSV
causetrace annotate <session_id> --task-type bug_fix --success
causetrace metadata <session_id>                 # Standardized runtime metadata
causetrace metadata-set <session_id> --runtime codex --model gpt-5
causetrace corpus snapshot                       # Reproducible corpus snapshot
causetrace corpus export                         # Dataset manifest JSON
causetrace corpus groups --label task_type       # Group sessions by label
causetrace corpus health                         # Milestone gaps and coverage
causetrace corpus origins                        # Source-origin coverage for Phase 3C
causetrace corpus benchmark                      # Benchmark manifest by metadata label
causetrace corpus benchmark verify <dir>         # Verify benchmark manifest integrity
causetrace corpus benchmark compare <a> <b>      # Compare two benchmark manifests
causetrace corpus taxonomy                       # Structural topology taxonomy
causetrace corpus readiness                      # Phase-3 research readiness gate
causetrace corpus materialize                    # Materialize canonical metadata sidecars
causetrace report <session_id>                   # Markdown research template
causetrace compare <session_a> <session_b>

Structural analysis is session-local: a parent ID not present in the loaded session marks a local boundary, so its child is analyzed as a local root. validate still reports missing non-root_ parent references as warnings.

Validated Cases

Data Model

Every event is a ToolEvent. The four causal fields (parent_event_id, session_id, event_type, caused_by) distinguish causetrace from flat logging systems.

Field	Description
`event_id`	UUID
`parent_event_id`	Causal parent (comma-separated for fan-in; may reference an external boundary)
`session_id`	Owning session
`tool_name`	e.g. `Bash`, `Read`, `Write`
`tool_input`	Serialized input arguments
`tool_output`	Serialized output
`timestamp`	ISO 8601
`duration_ms`	Execution time
`event_type`	`tool_call` / `reasoning` / `context_update` / `user_input`
`caused_by`	`user` / `reasoning` / event_id / semantic tag

CLI Reference

Command	Description
`causetrace timeline <id>`	Flat chronological view
`causetrace tree <id>`	Causal parent→child tree
`causetrace graph <id>`	Multi-parent DAG (fan-in)
`causetrace sessions`	List recorded sessions
`causetrace export <id>`	Export as JSON
`causetrace replay <id>`	Replay with provenance
`causetrace why <id> <eid>`	Trace causal chain from event
`causetrace enrich-sessions`	List Claude Code project sessions
`causetrace enrich <id> [--save]`	Enrich from Claude Code project session
`causetrace enrich-opencode-sessions`	List OpenCode DB sessions
`causetrace enrich-opencode <id> [--save]`	Enrich from OpenCode DB session
`causetrace enrich-codex-sessions`	List Codex CLI rollout sessions
`causetrace enrich-codex <id> [--save]`	Enrich from Codex CLI rollout session
`causetrace opencode [--save]`	Scan OpenCode logs
`causetrace aider [--save] -- [args]`	Run aider with tracing
`causetrace continue [--save]`	Scan Continue.dev logs
`causetrace codex [--save]`	Legacy Codex scan path; prefer `enrich-codex`
`causetrace copilot [--save]`	Scan GitHub Copilot agent logs
`causetrace validate [<id>]`	Validate JSONL integrity, references, and cycles
`causetrace stats [<id>]`	Show structural topology statistics
`causetrace roots [<id>]`	Show local roots and downstream metrics
`causetrace critical-path [<id>]`	Show longest local root-to-leaf chain
`causetrace patterns [<id>] [--json\|--csv]`	Show causal paths and transitions; CSV exports transitions
`causetrace annotate <id> [...]`	Store sidecar task/source/result metadata
`causetrace metadata <id>`	Show standardized runtime metadata sidecars
`causetrace metadata-set <id> [...]`	Set runtime metadata fields
`causetrace corpus snapshot`	Capture a reproducible corpus snapshot
`causetrace corpus export`	Export the corpus manifest as JSON
`causetrace corpus groups`	Group sessions by a metadata label
`causetrace corpus health`	Show milestone gaps and coverage
`causetrace corpus origins`	Show source-origin coverage for Phase 3C planning
`causetrace corpus benchmark`	Build a benchmark manifest from corpus labels
`causetrace corpus benchmark verify <dir>`	Verify benchmark manifest integrity
`causetrace corpus benchmark compare <a> <b>`	Compare two benchmark manifests
`causetrace corpus taxonomy`	Build a structural topology taxonomy
`causetrace corpus readiness`	Show phase-3 research readiness and blockers
`causetrace corpus materialize`	Materialize canonical metadata sidecars
`causetrace report <id>`	Generate a markdown research template
`causetrace compare <a> <b>`	Compare topology and transitions across sessions
`causetrace doctor`	Diagnose agent configuration and data sources
`causetrace demo`	Create and inspect a self-contained sample trace
`causetrace install-claude-hook`	Configure Claude Code capture hooks safely
`causetrace uninstall-claude-hook`	Remove only causetrace-managed hooks

Architecture

┌──────────────┐  ┌──────────────┐  ┌──────────────┐  ┌──────────────┐  ┌──────────────┐  ┌──────────────┐
│ Claude Code  │  │   OpenCode   │  │    Aider     │  │ Continue.dev │  │  Codex CLI   │  │   Copilot    │
│  (hooks)     │  │ (log tail)   │  │ (subprocess) │  │ (log tail)   │  │ (log tail)   │  │ (log tail)   │
└──────┬───────┘  └──────┬───────┘  └──────┬───────┘  └──────┬───────┘  └──────┬───────┘  └──────┬───────┘
       │                 │                 │                 │                 │                 │
       ▼                 ▼                 ▼                 ▼                 ▼                 ▼
┌────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                    TraceRecorder                                                    │
│                             (causal linking, storage)                                               │
└────────────────────────────────────────────────────────────────────────────────────────────────────┘
                                                │
                                                ▼
┌────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                                           JSONStore                                                │
│                                (append-only JSONL, no DB)                                          │
└────────────────────────────────────────────────────────────────────────────────────────────────────┘
                                                │
                                                ▼
┌────────────────────────────────────────────────────────────────────────────────────────────────────┐
│                              Tree / DAG Builders                                                    │
│                              Renderers / ReplayEngine                                               │
└────────────────────────────────────────────────────────────────────────────────────────────────────┘

Module	Responsibility
`causetrace/core.py`	Data model, `TraceRecorder`, `JSONStore`, tree/DAG builders, renderers, `ReplayEngine`
`causetrace/analysis.py`	Session-local topology, critical paths, windows, and causal patterns
`causetrace/annotation.py`	Sidecar metadata for task labels and comparison workflows
`causetrace/metadata.py`	Standardized runtime metadata sidecars
`causetrace/corpus.py`	Corpus snapshot, export, and grouping helpers
`causetrace/report.py`	Markdown research report templates
`causetrace/causality.py`	Temporal causal inference for unstructured logs
`causetrace/cli.py`	argparse CLI dispatching capture, analysis, annotation, and diagnostic commands
`causetrace/hooks/`	Agent-specific bridges and tailers
`causetrace/hooks/claude_code.py`	Claude Code hook bridge
`causetrace/hooks/claude_project_parser.py`	Claude Code project session parser
`causetrace/hooks/opencode_parser.py`	OpenCode SQLite DB session parser
`causetrace/hooks/codex_parser.py`	Codex CLI rollout JSONL parser
`causetrace/hooks/opencode_tailer.py`	OpenCode log tailer
`causetrace/hooks/aider_bridge.py`	Aider subprocess wrapper
`causetrace/hooks/continue_tailer.py`	Continue.dev log tailer
`causetrace/hooks/codex_tailer.py`	Codex CLI log tailer (legacy, use enrich)
`causetrace/hooks/copilot_tailer.py`	GitHub Copilot log tailer

Development

git clone https://github.com/milkoor/causetrace.git
cd causetrace
pip install -e ".[test]"
python -m pytest tests/ -v

License

MIT

Name		Name	Last commit message	Last commit date
Latest commit History 53 Commits
.claude/skills/gitnexus		.claude/skills/gitnexus
.githooks		.githooks
.github		.github
causetrace		causetrace
demo		demo
docs		docs
examples/traces		examples/traces
memory		memory
tests		tests
tools		tools
.gitignore		.gitignore
AGENTS.md		AGENTS.md
CHANGELOG.md		CHANGELOG.md
CLAUDE.md		CLAUDE.md
CODE_OF_CONDUCT.md		CODE_OF_CONDUCT.md
CONTRIBUTING.md		CONTRIBUTING.md
LICENSE		LICENSE
README.md		README.md
README.zh-CN.md		README.zh-CN.md
ROADMAP.md		ROADMAP.md
SECURITY.md		SECURITY.md
pyproject.toml		pyproject.toml

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causetrace

Use Cases

Showcase

Timeline (flat)

Causal Tree

Why (causal chain trace)

Multi-parent DAG

Supported Agents

Quick Start

Hook up Claude Code

Scan OpenCode logs

Analyze and validate sessions

Validated Cases

Data Model

CLI Reference

Architecture

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causetrace

Use Cases

Showcase

Timeline (flat)

Causal Tree

Why (causal chain trace)

Multi-parent DAG

Supported Agents

Quick Start

Hook up Claude Code

Scan OpenCode logs

Analyze and validate sessions

Validated Cases

Data Model

CLI Reference

Architecture

Development

License

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