Claude Code skill import rewrites `.claude/` paths to `.Codex/`, producing directories that don't exist

Summary

The external-agent import that copies Claude Code skills into ~/.agents/skills/
substitutes the token claude → Codex across the entire file body, including
inside literal filesystem paths. Prose retargeting is correct and useful; path
rewriting is not, because it produces paths that do not exist.

Repro

1. Have a Claude Code skill at ~/.claude/skills/example/SKILL.md whose body
   references a real path, e.g.:

   Session transcripts live in ~/.claude/projects/<slug>/
   See also .claude/commands/example.md
   

2. Let the Codex desktop onboarding import run ([desktop] external-agent-import-sync-enabled = true).

3. Read the imported copy at ~/.agents/skills/example/SKILL.md.

Actual

Session transcripts live in ~/.Codex/projects/<slug>/
See also .Codex/commands/example.md

Expected

The path should be left as ~/.claude/projects/<slug>/. It is an absolute
reference to a real directory owned by another tool, not an agent-relative path
that has a Codex equivalent.

Why this breaks

Two separate problems:

1. Wrong case. Codex is the display name; the directory is .codex. On
   case-insensitive APFS this happens to resolve, so it is silent on macOS and
   would break on a case-sensitive volume or on Linux.

2. No such directory — the real problem. Codex has no analogue for most of
   these. On my machine, after import:

   rewritten to	exists?
   ~/.codex/commands/	no
   ~/.codex/projects/	no
   ~/.codex/handoffs/	no
   ~/.codex/plans/	no
   ~/.codex/skills/	yes (coincidence — same directory name)

   So every imported skill that cites a ~/.claude/<subdir>/ path now sends the
   agent to a directory that does not exist. In my case that was 10 references
   across 5 imported skills.

The prose substitutions in the same pass are correct and worth keeping —
CLAUDE.md → AGENTS.md, "Claude Code UI" → "Codex UI". It is specifically the
path-shaped occurrences that should be exempt.

Suggested fix

Skip substitution for occurrences that look like filesystem paths — a match
preceded by /, ~/, or $HOME/, or immediately followed by /. A skill that
names another tool's data directory means that directory literally.

Failing that, at minimum substitute .claude → .codex rather than .Codex,
so the result is not also case-wrong.

Environment

• Codex CLI v0.149.0-alpha.4.1 (ChatGPT desktop, macOS)
• macOS 15 / Darwin 25.5.0, APFS (case-insensitive)
• Relevant module per binary strings: codex_tui::external_agent_config_migration

Workaround

Set external-agent-import-sync-enabled = false under [desktop] in
~/.codex/config.toml after the initial import, and repair the imported paths by
hand. The import is one-shot, so repairs survive normal codex exec use.

Start at codex_tui::external_agent_config_migration and reproduce the desktop external-agent import with a skill containing ~/.claude/projects/ and .claude/commands/ paths. Add or update regression coverage so path-shaped references remain literal while prose substitutions still occur, then verify the imported output.