custom-claude-skills/skills/distill-best-practices/SKILL.md

name, description, allowed-tools

name	description	allowed-tools
distill-best-practices	Cross-project best practices distillation. Reads changed memory files from all tracked projects and proposes additions, updates, or removals to claude-foundations/best-practices/. Run from any project — always targets claude-foundations as output. Interactive — presents proposals for approval before making changes.	Read, Edit, Write, Glob, Grep, Bash(git -C *), Bash(git rev-parse *), Bash(ls *), Bash(cat *), Bash(head *), Bash(date *)

Distill Best Practices Skill

You are extracting generalisable best practices from project-specific memory files across all tracked projects.

Pre-gathered context

CLAUDE_PROJECT_ROOT

!test -n "$CLAUDE_PROJECT_ROOT" && echo "$CLAUDE_PROJECT_ROOT" || echo "NOT_SET"

Distill state

!cat $CLAUDE_PROJECT_ROOT/projects/claude-foundations/best-practices/.distill-state.json 2>/dev/null || echo "{}"

Settings

!cat $CLAUDE_PROJECT_ROOT/projects/claude-foundations/settings.yaml 2>/dev/null || echo "Settings not found — CLAUDE_PROJECT_ROOT may not be set"

Current best-practices index

!cat $CLAUDE_PROJECT_ROOT/projects/claude-foundations/BESTPRACTICES.md 2>/dev/null || echo "Index not found"

Available best-practices files

!ls -1 $CLAUDE_PROJECT_ROOT/projects/claude-foundations/best-practices/ 2>/dev/null || echo "No best-practices directory"

Projects directory listing

!ls -1d $CLAUDE_PROJECT_ROOT/projects/*/ 2>/dev/null || echo "No projects directory"

Instructions

Step 0: Detect project root

Check the pre-gathered CLAUDE_PROJECT_ROOT value above. If it shows NOT_SET or the pre-gathered context is missing:

1. Walk up from the current working directory to find the highest parent directory containing a CLAUDE.md file — that is the project root.
2. Use that path as PROJECT_ROOT for all subsequent steps.

If CLAUDE_PROJECT_ROOT was set, use that value as PROJECT_ROOT.

The key paths derived from the root:

• Settings: <PROJECT_ROOT>/projects/claude-foundations/settings.yaml
• Best practices dir: <PROJECT_ROOT>/projects/claude-foundations/best-practices/
• Best practices index: <PROJECT_ROOT>/projects/claude-foundations/BESTPRACTICES.md
• Distill state: <PROJECT_ROOT>/projects/claude-foundations/best-practices/.distill-state.json

Step 1: Discover changes per project

Read settings.yaml (pre-gathered above, or read it now if Step 0 detected the root manually).

For each project in distill.projects, get its path: <PROJECT_ROOT>/<projects_dir>/<project_name>. Also process any distill.extra_projects entries — these have a path field relative to PROJECT_ROOT.

For each project (from both lists):

1. Get current HEAD: git -C <path> rev-parse HEAD
2. Look up last_sha from .distill-state.json for this project
3. If SHA matches → skip this project (no changes)
4. If last_sha exists → find changed files: git -C <path> diff --name-only <last_sha>..HEAD -- memory/
5. If last_sha is missing (first run) → list all memory files: ls <path>/memory/*.md

Filter to only memory/*.md files (exclude memory/log/ — those are raw, unprocessed).

If no projects have changes, say so and stop.

Step 2: Read changed memory files

For each changed memory file, read its full content using the Read tool.

Also identify which existing best-practices topic files cover the same domain. Use this mapping as a guide:

• gotchas-k8s.md → kubernetes.md
• gotchas-cilium.md → kubernetes.md
• gotchas-helm.md → helm.md
• gotchas-ansible.md → ansible.md
• gotchas-sops.md → secrets-management.md
• process-lessons.md → validation.md, debugging.md
• decisions.md → various (match by content)
• Other gotchas → match by topic or propose a new file

Read the matching best-practices files so you can compare.

Step 3: Analyse and propose

For each potential change, classify it:

• ADD: A lesson that is project-agnostic and valuable across projects. When generalising:

  • Strip project-specific details (IPs, namespace names, service names, hostnames)
  • Replace specifics with generic descriptions (e.g., "10.111.0.5" → "the DNS server IP")
  • Keep the principle and the reasoning — lose the implementation detail
  • Only promote lessons that would apply to at least one other project type

• UPDATE: An existing best-practice entry that has new supporting evidence, needs refinement, or should be expanded with a new example.

• REMOVE: A best-practice that has been invalidated — version-specific bug fixed, tool changed, approach superseded. Cross-reference: if the source gotcha was removed from the project's memory, the best-practice may be stale.

Step 4: Present proposals

Do NOT make any changes yet. Present a numbered list of proposals:

Proposals:

1. ADD to kubernetes.md: "<brief description of the new entry>"
   Source: cluster-bootstrap/memory/gotchas-k8s.md

2. UPDATE validation.md: "<what changes and why>"
   Source: cluster-bootstrap/memory/process-lessons.md

3. REMOVE helm.md: "<entry to remove and why it's stale>"
   Reason: Source gotcha removed in cluster-bootstrap commit abc1234

Wait for the user to approve, modify, or reject proposals. The user may say "all", give specific numbers, or ask for changes.

Step 5: Apply approved changes

For each approved proposal:

• ADD: Append the new entry to the target file, matching the existing style (heading level, bullet format, explanation depth)
• UPDATE: Edit the existing entry in place
• REMOVE: Delete the entry from the file

If a new best-practices topic file is needed:

• Create it following the format of existing files (top-level heading, subheadings per entry, 2-6 lines per entry)
• Add it to <PROJECT_ROOT>/projects/claude-foundations/BESTPRACTICES.md with a one-line description

Step 6: Update distill state

Write <PROJECT_ROOT>/projects/claude-foundations/best-practices/.distill-state.json:

{
  "version": 1,
  "last_run": "<ISO-8601 timestamp>",
  "projects": {
    "<project_name>": {
      "path": "<absolute_path>",
      "last_sha": "<current HEAD sha>",
      "last_run": "<ISO-8601 timestamp>"
    }
  }
}

Preserve entries for projects that weren't processed this run (no changes).

Step 7: Summary

Print:

• Projects scanned and number of changed memory files per project
• Number of proposals (add/update/remove)
• Number approved and applied
• Any new best-practices files created

Quality checks

• Best practices must be project-agnostic — no hardcoded IPs, namespaces, or service names
• Each entry should include the principle and reasoning, not just the rule
• Entries must be deduplicated against existing best-practices content
• The BESTPRACTICES.md must stay accurate after any file additions
• Proposals are always presented before applying — never auto-apply