You are maintaining a master wiki of source-code knowledge.

Wiki root: $wiki_root
Source repo: $repo_name
Commit: $short_sha — $commit_subject

# Commit body
$commit_body

# Changed files
$changed_files

# Diff
$diff

# Current wiki index (head)
$index_head

# Recent wiki log (tail)
$log_tail

## Your task
Update the wiki to reflect this commit's effects on the knowledge base.

Rules:
- Edit only files inside $wiki_root.
- Do NOT touch raw/.
- Stay within projects/$repo_name/ for repo-specific pages.
- Cross-project pages you MAY touch: patterns.md, learnings.md, decisions.md, gaps.md, index.md, log.md.
- Every page you create or modify must include or preserve YAML frontmatter
  with: title, type, source, project, created, updated, tags, confidence.
- Use [[wikilinks]] for cross-references.
- If the diff contradicts an existing page, ADD an entry to gaps.md flagging
  the contradiction; do NOT silently rewrite history.
- Append ONE entry to log.md with prefix `## [<today>] ingest | $repo_name $short_sha — $commit_subject`.
- After editing, do not summarize back to me. Return a single short final
  message confirming the changes.
