guillotine-mini: Command for Claude Code

.claude/commands/crash-bisection.md

crash-bisection is a command for Claude Code from evmts/guillotine-mini. It costs 16 tokens per session (2,013 once invoked), scanned A, original, MIT.

A debugging command that narrows a crash down by repeatedly enabling or disabling sections of code. Code bisection means splitting the suspected code into parts and testing each part to isolate the failing line.

In plain words
What is it for?
Use it with a reproducible crash, a suspected file, and an optional function name. It guides verification and testing after every code change before any fix is attempted.
Why use it?
Crashes may stop normal logging or produce unclear symptoms, making ordinary debugging unreliable. Methodical bisection reduces the search until the exact line is identified.

Command for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: model in frontmatter.

This is evmts/guillotine-mini's own configuration. It tells Claude Code how to work on guillotine-mini itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything guillotine-mini configures →

Reuse

Borrowing it

Nothing to install: this file belongs to evmts/guillotine-mini. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/evmts/guillotine-mini/main/.claude/commands/crash-bisection.md
Clone the repo
git clone --depth 1 https://github.com/evmts/guillotine-mini

Made for: Claude Code.

Wrote this? Show the measurements

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agentmods badge for crash-bisection

README.md
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<a href="https://agentmods.dev/commands/evmts/guillotine-mini/crash-bisection"><img src="https://agentmods.dev/badge/commands/evmts/guillotine-mini/crash-bisection/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.

agentmods 80×15 button for crash-bisection

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<a href="https://agentmods.dev/commands/evmts/guillotine-mini/crash-bisection"><img src="https://agentmods.dev/badge/commands/evmts/guillotine-mini/crash-bisection.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 16 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,013 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5.1 $0.00016 $0.02013
Opus 5.5 $0.00006 $0.00805
Sonnet 5.5 $0.00003 $0.00403
Haiku 4.5 $0.00002 $0.00201

Measured 2mo ago against content hash 2b5423e17d01, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

crash-bisection 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 2mo 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.

.claude/commands/crash-bisection.md · 231 lines

How it starts

The opening of the file, as written. The whole thing — 231 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Crash Bisection Debugging Command

Systematically isolate the exact line of code causing a crash through methodical bisection (commenting/uncommenting code). This process will ALWAYS succeed if followed precisely.

CRITICAL: Unwavering Methodology

YOU MUST BE ABSOLUTELY STUBBORN AND METHODICAL. DO NOT DEVIATE.

  • ❌ DO NOT try to add debug logging (crashes swallow output)
  • ❌ DO NOT try to fix the issue until the exact line is found
  • ❌ DO NOT skip steps or make assumptions
  • ❌ DO NOT re-enable all code if something doesn't work
  • ❌ DO NOT report back until the EXACT line is identified
  • ✅ DO follow the bisection process EXACTLY as described
  • ✅ DO continue methodically even if it seems tedious
  • ✅ DO test after EVERY single change

Required Information from User

Ask the user to provide:

  1. Test command: The exact command that reproduces the crash (e.g., zig build test-opcodes -Dtest-filter='ADD opcode')
  2. File path: The file suspected to contain the crash (or use $ARGUMENTS if provided)
  3. Function name (optional): Specific function to start with if known
  4. Crash symptoms: What happens (segfault, panic, hang, etc.)

Phase 1: Initial Verification

  1. Run the test command to confirm the crash reproduces
  2. Note the exact error message or crash behavior
  3. You do not need to create a backup of the file, we already use version control for that

Phase 2: Function-Level Bisection

  1. Identify all functions in the suspect file

  2. Replace function bodies with stubs one by one, testing after each:

    pub fn someFunction(args: Type) ReturnType {
        // [entire function body commented out]
        // Return stub value to keep compilation working:
        return undefined; // or appropriate default/zero value
    }
    

    For error unions: return error.NotImplemented; For optionals: return null; For void: just return For noreturn: unreachable; or @panic("stub");

  3. When the crash disappears after stubbing a function, YOU FOUND THE CULPRIT FUNCTION

  4. Restore all other functions to their original state

  5. Keep only the culprit function for investigation

Read the full file on GitHub · 231 lines

Changes

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.

  1. 2mo ago First seen · 231 lines · 16 tokens per session scan A 2b5423e17d01

Subscribe to this mod's changes

crash-bisection is a command published in the GitHub repository evmts/guillotine-mini (11 stars, last pushed 2mo ago), licensed MIT. It adds 16 tokens to every session and 2,013 once invoked, about $0.0001 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 2026-08-31.

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