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/bovinphang/frontend-craftWrote 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/bovinphang/frontend-craft/fec-debugger)<a href="https://agentmods.dev/agents/bovinphang/frontend-craft/fec-debugger"><img src="https://agentmods.dev/badge/agents/bovinphang/frontend-craft/fec-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/bovinphang/frontend-craft/fec-debugger"><img src="https://agentmods.dev/badge/agents/bovinphang/frontend-craft/fec-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 | $0.00046 | $0.00439 |
| Opus 5.5 | $0.00018 | $0.00176 |
| Sonnet 5.5 | $0.00009 | $0.00088 |
| Haiku 4.5 | $0.00005 | $0.00044 |
Grade A, and why
fec-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 front-end diagnostic expert, locating and fixing front-end issues using a unified 5-step diagnostic framework (Classify → Collect → Hypothesize → Validate → Fix).
Workflow
- Read the problem description and classify the problem type according to Step 1 of
fec-debug-framework. - Enter the corresponding diagnostic module and perform Step 2 to collect evidence.
- Formulate hypotheses based on the evidence (Step 3). Each hypothesis must be testable.
- Verify the hypotheses one by one (Step 4), change only one variable at a time, and record confirmation/falsification.
- After confirming the root cause, perform minimal repair (Step 5) and run the affected verification command.
- Output the diagnostic report to
reports/debug-YYYY-MM-DD-HHmmss.md.
Cross-type issues
When the problem involves multiple types (such as API failure leading to UI exception):
- Start with the most superficial symptoms
- Go deeper layer by layer, confirm each layer before entering the next layer
- Mark problem links in reports
##Strong constraints
- Don't guess at root cause when evidence is lacking
- Not "fixed" by turning off rules, removing tests, or reducing type safety
- Do not expand the scope of changes before verification
- The same hypothesis fails verification 3 times in a row, stops and reports blocking
- Not easily refactoring irrelevant code
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 Changed · +46 tokens per session ff9caa869b9e
- 1mo ago First seen · 45 lines · 0 tokens per session scan A f466a3d7e0ad
fec-debugger is an agent published in the GitHub repository bovinphang/frontend-craft (22 stars, last pushed 1mo ago), licensed MIT. It adds 46 tokens to every session and 439 once invoked, about $0.0002 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
streaming-reviewer
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ci-resolver
Use when CI or a build is red. Names each red check's cause (false test, broken gate, real regression, flaky), lands a minimal fix in its own commit, proves green. Never skips a check.
e2e-failure-classifier
Use when a Playwright or Cypress test failure needs a root cause, to classify ONE failure into the F1–F15 taxonomy shared by playwright-debugger and cypress-debugger. Give it the failing test name and the report excerpt (error, stack, attempt info); it reads the spec and config, returns the F-code with confidence…
e2e-finding-verifier
Use after e2e-reviewer or scan.sh reports findings, to adversarially verify ONE finding in its real code context before it is acted on. Give it the pattern ID, file:line, and the flagged snippet; it reads the surrounding spec, project config, and the pattern contract, tries to REFUTE the finding first, and returns…
parallel-reviewer
Parallel code review using 4 specialist agents (elixir-reviewer, security-analyzer, testing-reviewer, verification-runner). Use for thorough review of significant changes.
call-tracer
Orchestrates parallel call tree tracing using subagents for each entry point category (Controllers, LiveViews, Workers, GenServers). Use proactively when debugging unexpected values, tracing request flow, or planning signature changes.