Migrate Tags

Usage

• /migrate-tags — Scan vault, present a migration plan, prompt to confirm.
• /migrate-tags <path> — Migrate a single file.
• /migrate-tags <folder> — Migrate all .md files under a folder.
• /migrate-tags --dry-run — Show what would change without writing.

Why this skill exists

Obsidian supports two tag styles:

• Body tags: #frontend written inline in note text.
• Frontmatter tags: a YAML tags: list at the top of the file.

Bases can filter on the frontmatter style (file.hasTag("frontend")) but not the body style reliably. Migrating one to the other makes tags queryable in Bases views — e.g. a "People with #mobile tag" view becomes trivial once everyone's @Name.md has tags: [mobile].

This skill is a one-shot migration utility plus an ongoing cleanup tool for new notes.

Workflow

Step 1: Discover candidates

Use obsidian tags format=json to enumerate all tags + their usage counts and source files. Identify files where:

• A body #tag exists, AND
• The same tag is NOT already present in frontmatter tags:.

These are the migration candidates.

Step 2: Present the plan

Show a numbered table grouped by file:

| # | File | Body tags to migrate | Existing frontmatter tags |
|---|------|----------------------|---------------------------|
| 1 | Teams/People/@Jane Doe.md | #team-engineering, #backend | (none) |
| 2 | Teams/People/@John Smith.md | #team-engineering, #remote | (none) |
| 3 | Misc/Reading.md | #to-read, #book | (none) |

Ask the user: "all", "1,2", "none", or per-file picks.

Step 3: Apply migration

For each confirmed file:

1. Read the file body, collect all #tag patterns (respecting word boundaries — #tag not https://foo.com/path#section).
2. Use obsidian property:set name=tags value='["a","b","c"]' type=list path="<file>" to write the frontmatter list. If tags: already exists, merge (don't overwrite). See frontmatter-mutations.
3. Optionally remove the body #tag patterns (default: leave them — Obsidian indexes both, body tags don't hurt). Add a --strip-body flag for users who want clean bodies.

Step 4: Verify

Run obsidian property:read name=tags path="<file>" on each migrated file to confirm the write. Spot-check that no tags were lost.

Step 5: Commit

See /commit. Commit message: chore: migrate body #tags to frontmatter tags: list (N files).

Important Notes

• Idempotent: re-running on already-migrated files is a no-op.
• Don't strip body tags by default — users may rely on visible tags in the body for in-note navigation. Opt-in via --strip-body.
• Tag normalization: leave tag names as-is. Don't auto-convert #team-engineering → team-engineering (the leading # is stripped automatically; nothing else).
• Nested tags (#team/engineering) are preserved.
• Tags inside code blocks are skipped — they're literal, not Obsidian tags.
• After running on People files, People.base per-team views can use file.hasTag("team-X") as an alternative to the file.hasLink(file("Teams/+X.md")) filter (which works but is more verbose).