Learn From Fix

What the source does

• FilesystemNone observedNo reads or writes in the source
• NetworkNone observedNo outbound calls in the source
• ShellNone observedNo commands run in the source
• DependenciesPinnedNothing floats
• SecretsNone foundNo keys in source

Five audit layers

Gates applied: no behavioural pass.

Audit 0.4.1 · source sha 492f17636999 · 18 Oct 2026Report an issue or request a re-scan

• Publisheroliver-kriska GitHub userOwner of the repository this skill is read from
• Source folderoliver-kriska/claude-elixir-phoenix/plugins/elixir-phoenix/skills/learn-from-fixThe exact folder we audited
• LicenceMITAs the repository states it
• Commit pinned for this verdict492f17636999A new audit runs when the source changes
• Repository statusNot archivedLast push 2 days ago
• Sandboxed runNot runSkills are read, not executed; layer L4 is skipped

Its description: Capture Elixir/Ecto/LiveView lessons and Hex API rules. Use after corrections or when asked to document learning, record a lesson, prevent a fixed mistake, or remember package guidance with --library.

---
name: learn-from-fix
description: Capture Elixir/Ecto/LiveView lessons and Hex API rules. Use after corrections or when asked to document learning, record a lesson, prevent a fixed mistake, or remember package guidance with --library.
effort: low
argument-hint: "[--library <hex-package> --scope personal|project] <lesson>"
---

# Learn From Fix

After fixing a bug or receiving a correction, capture the lesson
to prevent future mistakes.

## Usage

```
/phx:learn-from-fix Fixed N+1 query in user listing - was missing preload
/phx:learn-from-fix String vs atom key mismatch in params handling
/phx:learn-from-fix LiveView assign_async needs render_async in tests
/phx:learn-from-fix --library ical --scope personal ICal.to_ics output needs CRLF line endings
/phx:learn-from-fix --library ical --scope project Use method: "PUBLISH" for calendar feeds
```

## Workflow

### Step 1: Verify the Lesson

Persist only one of:

- A completed fix verified by tests, reproduction, or user confirmation
- An explicit rule the user taught or asked to save

Stop without writing if neither condition is met.
Do not save a hypothesis, unverified workaround, investigation narrative, or
unsolved error. Use `/phx:compound` for a detailed completed investigation.
Capture the root cause as a concise actionable rule, not the symptom.

### Step 2: Select the Route

When both `--library <package>` and `--scope personal|project` are present,
use the [Library Route](#library-route). Require both flags; do not guess scope.
For the skill directory only, trim surrounding whitespace and lowercase the
package name. Preserve underscores when forming directory names
(`phoenix_live_view` becomes `hex-phoenix_live_view`).
Validate the normalized name against `^[a-z][a-z0-9_]+$`. If it does not match,
ask for a valid Hex package identifier instead of replacing characters or
inventing a name. Use the trimmed original identifier, not the normalized
directory name, to look up `mix.lock`.

Without `--library`, use the [General Correction Route](#general-correction-route).

### Step 3: Check Existing Knowledge

Check if already documented:

- Grep project CLAUDE.md and `~/.claude/CLAUDE.md` for the pattern keyword
- Check auto-memory files for similar lessons
- For library lessons, inspect both
  `~/.claude/skills/hex-<package>/SKILL.md` and
  `.claude/skills/hex-<package>/SKILL.md`
- Read `${CLAUDE_SKILL_DIR}/references/common-mistakes.md` (read-only plugin
  reference)

Do not duplicate the same lesson across CLAUDE.md, memory, and a package skill.
If the same rule exists, merge wording or report it as already captured.

## Library Route

Plugin files are read-only: files under `~/.claude/plugins/` are cached
and get overwritten on updates. Package skills are user-owned files, never
plugin cache files.

### Resolve Scope and Precedence

| `--scope` | Canonical destination |
|-----------|-----------------------|
| `personal` | `~/.claude/skills/hex-<package>/SKILL.md` |
| `project` | `.claude/skills/hex-<package>/SKILL.md` |

Personal skills override same-named project skills. If a personal
`hex-<package>` skill exists, never unknowingly create or update a shadowed
project skill: explain the conflict and ask whether to update personal scope or
keep distinct project-only knowledge. If project scope already exists before a
personal write, warn that the new skill will shadow it and offer to merge or
move it. Maintain one canonical skill per package unless the user explicitly
needs distinct scope-specific rules; never create one skill per lesson.

### Read the Locked Version

Inspect `mix.lock` for the package. Record the exact locked version when found.
If it is absent, say the lesson is not tied to a locally locked version and do
not invent one. Qualify version-sensitive rules. When two verified rules
conflict across versions, preserve both with explicit version ranges instead of
replacing either.

### Create or Safely Update the Skill

For a new package skill, create:

```markdown
---
name: hex-<package>
description: <Package/module/API/task trigger terms for this knowledge>
user-invocable: false
---

# <Package> Knowledge

## Verified Rules

- **<Rule>** (verified with <package> <version>): <actionable guidance>
```

Make the description precise: include the Hex package, Elixir module names,
important APIs/file formats, and tasks that should trigger this knowledge.
Activation is model-selected from this description; package presence in
`mix.lock` does not guarantee activation.

Before updating an existing skill, read all of it. Preserve unrelated and
hand-authored sections. Merge semantically identical rules. If safe merging is
unclear, show the conflict and ask instead of overwriting content.

Do not add `paths:` to a personal package skill by default: it is a file-path
activation gate, not a dependency predicate. Add `paths:` only to project scope
when explicitly appropriate and meaningful package-specific paths exist.

## General Correction Route

Choose the narrowest non-library destination:

| Scope | Write to | Example |
|-------|----------|---------|
| This project | Project CLAUDE.md | "Never use raw SQL in this app" |
| This project across sessions | Project-keyed auto-memory | "jsonb uses string keys" |
| All your projects | `~/.claude/CLAUDE.md` personal instructions | "Prefer explicit error tuples" |
| Detailed completed fix | `.claude/solutions/` via `/phx:compound` | Debugging narrative |

For project or personal instructions, preserve existing content and append
`**RULE NAME** — Do NOT [bad]. Instead [good]` under the relevant category. Use
personal instructions only for rules that should load in every project. For
auto-memory, append to the project-keyed
`~/.claude/projects/{project-hash}/memory/MEMORY.md`:

```markdown
### Lesson: [Title]
- **Pattern**: Do NOT [bad] — instead [good]
- **Why**: [root cause explanation]
```

If the lesson is universal to the plugin rather than one project or package,
suggest a plugin co

Excerpt, first 6,000 characters of SKILL.md, verbatim from the audited commit. It is text from someone else’s repository, quoted so you can judge it before your agent reads it.

git clone https://github.com/oliver-kriska/claude-elixir-phoenix
git -C claude-elixir-phoenix checkout 492f17636999

Works in

1. 2026-10-18
   ✓SAFE B 89 / 100

   first audit · source 492f17636999

Questions about Learn From Fix

• github.com/oliver-kriska/claude-elixir-phoenix/tree/main/plugins — the audited source at commit 492f17636999 and every finding aboveObserved · 18 Oct 2026

Spotted something wrong? Report a correction · Methodology