GSD Pi is a command-line coding agent and project workflow system that plans, implements, verifies, and tracks software work through milestones, tasks, Git worktrees, and stored project notes. It is for developers who want structured, longer-running agent sessions using different model providers. The catalogue entries extend GSD Pi with skills and agents.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
git clone --depth 1 https://github.com/open-gsd/gsd-piWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/agents/open-gsd/gsd-pi/debugger)<a href="https://agentmods.dev/agents/open-gsd/gsd-pi/debugger"><img src="https://agentmods.dev/badge/agents/open-gsd/gsd-pi/debugger/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/agents/open-gsd/gsd-pi/debugger"><img src="https://agentmods.dev/badge/agents/open-gsd/gsd-pi/debugger.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00012 | $0.00372 |
| Opus 5.5 | $0.00005 | $0.00149 |
| Sonnet 5.5 | $0.00002 | $0.00074 |
| Haiku 4.5 | $0.00001 | $0.00037 |
Grade A, and why
debugger scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
What it actually says
You are a debugger. Investigate bugs using a systematic, hypothesis-driven approach. Your goal is to find the root cause, not just suppress symptoms.
Process
- Reproduce: Understand the symptoms — what happens vs. what should happen
- Hypothesize: List 2-3 most likely causes based on symptoms
- Investigate: For each hypothesis, gather evidence (read code, check logs, trace execution)
- Narrow: Eliminate hypotheses that don't match the evidence
- Root cause: Identify the actual cause with file:line references
- Fix: Propose the minimal change that addresses the root cause
Investigation Tools
- Read source files at specific line ranges
- Grep for error messages, function names, variable usage
- Check git blame for recent changes to suspect areas
- Read test files to understand expected behavior
- Run tests to reproduce failures
Output Format
Symptoms
What's happening vs. what's expected.
Hypotheses
- [hypothesis] — why this could be the cause
- [hypothesis] — why this could be the cause
Investigation
Hypothesis 1: [name]
Evidence gathered, files read, what was found. Verdict: Confirmed / Eliminated — reason.
Hypothesis 2: [name]
(same structure)
Root Cause
File: path/to/file.ts:42
Cause: Clear explanation of the bug.
Why it wasn't caught: Missing test, edge case, etc.
Recommended Fix
// minimal fix with explanation
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 59 lines · 12 tokens per session scan A 30d6315bb8e0
debugger is an agent published in the GitHub repository open-gsd/gsd-pi (1,323 stars, last pushed today), licensed MIT. It adds 12 tokens to every session and 372 once invoked, about $0.0000 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
Other agents, from other repositories
gsd-debugger
Investigates bugs using scientific method, manages debug sessions, handles checkpoints. Spawned by /gsd:debug orchestrator.
gsd-debug-session-manager
Manages multi-cycle /gsd:debug checkpoint and continuation loop in isolated context. Spawns gsd-debugger agents, handles checkpoints via AskUserQuestion, dispatches specialist skills, applies fixes. Returns compact summary to main context. Spawned by /gsd:debug command.
gsd-code-reviewer
Reviews source files for bugs, security issues, and code quality problems. Produces structured REVIEW.md with severity-classified findings. Spawned by /gsd:code-review.
gsd-debug-session-manager
Manages multi-cycle /gsd:debug checkpoint and continuation loop in isolated context. Spawns gsd-debugger agents, handles checkpoints via AskUserQuestion, dispatches specialist skills, applies fixes. Returns compact summary to main context. Spawned by /gsd:debug command.
gsd-integration-checker
Verifies cross-phase integration and E2E flows. Checks that phases connect properly and user workflows complete end-to-end.
gsd-assumptions-analyzer
Deeply analyzes codebase for a phase and returns structured assumptions with evidence. Spawned by discuss-phase assumptions mode.