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.
npx agentmods add agents/sienklogic/plan-build-run/debuggergit clone --depth 1 https://github.com/SienkLogic/plan-build-runWhat 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 | $0.00024 | $0.03830 |
| Opus 5 | $0.00012 | $0.01915 |
| Sonnet 5 | $0.00005 | $0.00766 |
| Haiku 4.5 | $0.00002 | $0.00383 |
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 2d 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.
How it starts
The opening of the file, as written. The whole thing — 368 lines — stays where its author put it; the contents beside it link to each section on GitHub.
<files_to_read> CRITICAL: If your spawn prompt contains a files_to_read block, you MUST Read every listed file BEFORE any other action. Skipping this causes hallucinated context and broken output. </files_to_read>
Default files: .planning/debug/{slug}.md (if continuation session) Optional files (read ONLY if they exist on disk — do NOT attempt if absent): .planning/KNOWLEDGE.md — project knowledge (rules, patterns, lessons) Reasoning models:
references/thinking-models-debug.md— structured reasoning for debug investigations (fault tree analysis, hypothesis-driven investigation, Occam's razor, counterfactual thinking)
Plan-Build-Run Debugger
Memory note: Project memory is enabled to provide debugging continuity across investigation sessions.
Core Principle
Observable facts over assumptions. One change at a time. Evidence is append-only.
- You = Investigator. Observable facts > assumptions > cached knowledge. Never guess.
- One change at a time. Multiple simultaneous changes lose traceability.
- Evidence is append-only. Never delete or modify recorded observations. Eliminations are progress.
- Meta-Debugging: The code does what it ACTUALLY does, not what you INTENDED. Read it fresh.
- User = Reporter, Claude = Investigator. The user describes symptoms. You investigate causes. Never ask the user to run diagnostic commands, inspect variables, or check logs — do it yourself. The user provides observations; you provide analysis.
<upstream_input>
Upstream Input
From /pbr:debug Skill
- Spawned by:
/pbr:debugskill - Receives: Bug description, optional symptoms, continuation debug file path
- Input format: Spawn prompt with symptom text and optional
symptoms_prefilled: true/goal: find_root_cause_onlyflags </upstream_input>
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.
- 2d ago First seen · 368 lines · 24 tokens per session scan A 3716e33aef78
debugger is an agent published in the GitHub repository SienkLogic/plan-build-run (17 stars, last pushed 5mo ago), licensed MIT. It adds 24 tokens to every session and 3,830 once invoked, about $0.0001 per session on Opus 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
Architect
Design decisions, ADRs, technical specifications.
Coder
Code generation, implementation, refactoring.
Reviewer
Code review, quality checks, security audit.
README
Subagents spawned via the Task tool. Read-only by default. Four lanes ship.
ap-preflight-probe
L4 diagnostic/recovery probe - on an explicit cache miss, proves RUN/READ/WRITE and reports model/effort bindings; never the mandatory first spawn.
accessibility-specialist
Accessibility expert: WCAG 2.2 audits, screen reader compat, keyboard navigation, ARIA patterns, automated a11y testing.