How do I install the Evanflow Debug skill?

Run npx skillmds@latest add evanklem/evanflow-debug in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Is Evanflow Debug free to use?

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Who published Evanflow Debug?

evanklem (@evanklem) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Evanflow Debug by evanklem — Agent Skill

Name: Evanflow Debug
Author: evanklem

Evanflow Debug

Root-cause discipline for bugs, test failures, and unexpected behavior. Embedded grill on the hypothesis before writing fix code. Use when encountering any bug, failing test, or behavior that doesn't match expectation.

evanklem b6c9112 3.0 KB Updated Sep 17, 2026

File contents

EvanFlow: Debug

Vocabulary

See evanflow meta-skill.

When to Use

Test failing
User reports unexpected behavior
Production error
Code does the wrong thing under specific conditions
Anything where the immediate symptom isn't the root cause

SKIP when: the cause is obvious and the fix is one line. Don't ceremonialize trivial bugs.

The Flow

1. Reproduce

Get the exact reproduction: input, environment, steps
Reproduce locally if possible. If you can't reproduce, the bug is unverified — say so before proceeding.

2. Form a Hypothesis

State the hypothesis explicitly:

"I think the bug is in : because when X happens, Y is supposed to happen but instead Z does."

A vague "probably the validation" is not a hypothesis.

3. Embedded Grill — Challenge the Hypothesis

Before writing any fix, ask:

Symptom vs. cause: "Is this where the bug manifests, or where it originates? Trace one step further upstream."
Coverage: "What other code paths share this root cause? Will the fix here leave those paths broken?"
Reversibility: "Does the fix have the same blast radius as the bug, or wider?"
Test gap: "Why didn't a test catch this? Is the test missing, wrong, or misaligned with real behavior?"
Domain check: "Is the bug actually behaving correctly per spec, and the spec is wrong?"

4. Verify the Hypothesis Before Fixing

Add an instrument (log, breakpoint, test assertion) that proves the hypothesis right or wrong. Watch the instrument fire. If it doesn't, the hypothesis is wrong — go back to step 2.

5. Write a Failing Test First

The test should fail because the bug exists. This is a vertical-slice TDD application — see evanflow-tdd.

6. Fix at the Root

Fix where the root cause originates, not where the symptom appears. If the fix is far from the symptom, leave a comment explaining the WHY (this is one of the few cases where a code comment earns its keep).

7. Verify the Test Passes

Run the test. Run the broader suite. Confirm no regressions.

Hard Rules

No fix without a failing test that demonstrates the bug. (Same TDD principle as evanflow-tdd.)
Fix the root, not the symptom. Symptom-fixes are how bugs metastasize.
Never auto-commit. A fix gets staged; user confirms before commit.
If you can't reproduce, say so. Don't fix invisible bugs.

Hand-offs

Fix complete, tests pass → if mid-plan, return to evanflow-executing-plans. If standalone debug, report what was fixed and STOP. The user decides whether to commit or take further action.
Discovered an architectural issue → evanflow-improve-architecture
Discovered the spec is wrong → evanflow-brainstorming to align on intended behavior

---name: evanflow-debugdescription: Root-cause discipline for bugs, test failures, and unexpected behavior. Embedded grill on the hypothesis before writing fix code. Use when encountering any bug, failing test, or behavior that doesn't match expectation.---# EvanFlow: Debug## VocabularySee `evanflow` meta-skill.## When to Use- Test failing- User reports unexpected behavior- Production error- Code does the wrong thing under specific conditions- Anything where the immediate symptom isn't the root cause**SKIP when:** the cause is obvious and the fix is one line. Don't ceremonialize trivial bugs.## The Flow### 1. Reproduce- Get the exact reproduction: input, environment, steps- Reproduce locally if possible. If you can't reproduce, the bug is unverified — say so before proceeding.### 2. Form a HypothesisState the hypothesis explicitly:> "I think the bug is in <file>:<line> because when X happens, Y is supposed to happen but instead Z does."A vague "probably the validation" is not a hypothesis.### 3. Embedded Grill — Challenge the HypothesisBefore writing any fix, ask:- **Symptom vs. cause**: "Is this where the bug *manifests*, or where it *originates*? Trace one step further upstream."- **Coverage**: "What other code paths share this root cause? Will the fix here leave those paths broken?"- **Reversibility**: "Does the fix have the same blast radius as the bug, or wider?"- **Test gap**: "Why didn't a test catch this? Is the test missing, wrong, or misaligned with real behavior?"- **Domain check**: "Is the bug actually behaving correctly per spec, and the spec is wrong?"### 4. Verify the Hypothesis Before FixingAdd an instrument (log, breakpoint, test assertion) that proves the hypothesis right or wrong. **Watch the instrument fire.** If it doesn't, the hypothesis is wrong — go back to step 2.### 5. Write a Failing Test FirstThe test should fail because the bug exists. This is a vertical-slice TDD application — see `evanflow-tdd`.### 6. Fix at the RootFix where the root cause originates, not where the symptom appears. If the fix is far from the symptom, leave a comment explaining the WHY (this is one of the few cases where a code comment earns its keep).### 7. Verify the Test PassesRun the test. Run the broader suite. Confirm no regressions.## Hard Rules- **No fix without a failing test that demonstrates the bug.** (Same TDD principle as evanflow-tdd.)- **Fix the root, not the symptom.** Symptom-fixes are how bugs metastasize.- **Never auto-commit.** A fix gets staged; user confirms before commit.- **If you can't reproduce, say so.** Don't fix invisible bugs.## Hand-offs- Fix complete, tests pass → if mid-plan, return to `evanflow-executing-plans`. If standalone debug, **report what was fixed and STOP**. The user decides whether to commit or take further action.- Discovered an architectural issue → `evanflow-improve-architecture`- Discovered the spec is wrong → `evanflow-brainstorming` to align on intended behavior

Frequently asked questions