fix(codex/oauth): resolve cache & credential paths under the real home on macOS (split 2 of #27)

[kdegeek]

Summary

Salvaged from #27 as a small standalone patch against current main, per @MarlBurroW's split suggestion. Blocker 3 (the getRealHome boot-crash) is already fixed on main, so this is purely the path-resolution improvement the review called out.

The bug: on macOS, getRealHome() returns /home/$USER (because USER is set and there's no snap path to strip) while the real home is /Users/$USER. A single REAL_HOME-derived path therefore misses the Codex CLI files entirely. The fix searches the plain env HOME first, then the snap-adjusted REAL_HOME:

• openai-codex.ts — models_cache.json is read from a candidate list, extracted as the pure, tested modelsCacheCandidates().
• _codex-auth.ts — ~/.codex/auth.json searched under env HOME then REAL_HOME.
• _anthropic-oauth-auth.ts — the three Claude credential filenames searched under env HOME then REAL_HOME.

Every home value is run through normalizeAbsoluteHome before use, so the builders never emit a relative candidate. When env HOME and REAL_HOME coincide (the common Linux case), the candidate lists collapse to the original single set — behavior there is unchanged.

Validation

• bun run typecheck — PASS
• bun run test — PASS (added modelsCacheCandidates unit tests: macOS ordering, dedup, relative-home rejection)
• bun run build — PASS
• git diff --check — PASS
• CodeRabbit review — the two normalizeAbsoluteHome-consistency notes it raised are addressed in this branch.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR improves macOS (and nonstandard home) path resolution for Codex and Claude CLI cache/credential discovery by searching candidate paths under the plain env HOME first, then falling back to the snap-adjusted REAL_HOME, while ensuring only absolute home paths are used.

Changes:

• Add modelsCacheCandidates() and use an ordered candidate list to read Codex models_cache.json from HOME then REAL_HOME.
• Update Codex CLI auth and Claude Code credential discovery to search under HOME first, then REAL_HOME, with absolute-home validation.
• Add unit tests covering modelsCacheCandidates() ordering, deduplication, and relative-home rejection.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
src/server/llm/llm/openai-codex.ts	Reads Codex model cache from an ordered HOME→REAL_HOME candidate list with absolute-home normalization.
src/server/llm/llm/openai-codex.test.ts	Adds unit tests for candidate ordering/dedup and rejecting relative homes.
src/server/llm/llm/_codex-auth.ts	Searches for ~/.codex/auth.json under env HOME first, then REAL_HOME, with absolute-home validation.
src/server/llm/llm/_anthropic-oauth-auth.ts	Searches for Claude credential files under env HOME first, then REAL_HOME, with absolute-home validation.

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[kdegeek]

Addressed the Copilot note about normalizeAbsoluteHome being duplicated: extracted it (plus the identical getRealHome and the resolved REAL_HOME) into a shared src/server/llm/llm/_home-paths.ts and imported it from the three modules. Underscore-prefixed so it isn't picked up as a provider; no behavior change, and it removes the pre-existing getRealHome triplication too.