fix(claude): honor CLAUDE_CONFIG_DIR when resolving the resume session id

[AThraen]

Fixes restored Claude sessions failing with No conversation found with session ID: <uuid>, leaving a bare shell prompt behind.

Root cause

ClaudeSessionService hardcoded ~/.claude as Claude's data directory:

Path.Combine(UserProfile, ".claude", "projects", projectDir)

Claude Code honors CLAUDE_CONFIG_DIR, and when it's set, conversations live under $CLAUDE_CONFIG_DIR/projects/ instead. A machine that has ever run without the env var keeps a stale ~/.claude/projects/ tree — so GetLastSessionId returned the newest id from the wrong store: a real, valid-looking UUID that current Claude has no record of.

This is why it looked like Claude had changed how --resume works. It hasn't; only where conversations are stored moved.

Evidence from the reporting machine

CLAUDE_CONFIG_DIR is set at User scope, so CodeShellManager.exe inherits it. For one project folder:

Store	Newest .jsonl
~/.claude (stale, frozen ~2 months)	6270d0e9-971a-44ad-81b9-cf89434ab1cf ← exactly the id in the error
~/.claude-work (live)	8eaf0a22-4f5d-45a4-a579-0ccf20553e27, modified same day

Change

• ResolveClaudeHome(configDir, userProfile) — CLAUDE_CONFIG_DIR when set, else ~/.claude.
• GetLastSessionId gains an internal overload taking the resolved home, so the lookup is testable without mutating process environment or depending on the real user profile. Public signature unchanged.

This deliberately does not fall back to the legacy directory when the resolved one has no session — returning null starts a fresh conversation, which is correct. Falling back would reintroduce the bogus-id failure.

Scope

Does not fix #75 (the same-folder resume race, where two sessions in one folder both resolve to the same id and the first session's own write poisons the lookup for the second). That's a separate root cause in the same code path; the durable fix there is persisting a ClaudeSessionId per session and launching with --session-id. This PR only ensures we read the right directory.

Verification

• 9 new unit tests — env resolution (set / null / blank), stale-vs-live store selection, missing and empty project dirs, path→project-dir-name mapping, and the real on-disk layout where a <session-id>/ subdirectory and a memory/ dir sit next to <session-id>.jsonl
• 215/215 tests pass; app builds clean
• Written test-first; watched each fail

Manual check worth doing before merge: restart CodeShellManager and confirm sessions resume rather than erroring. I verified the id resolution against the real filesystem but did not perform a live --resume (that would have written into an in-use conversation).

🤖 Generated with Claude Code