Session picker: sort order, UUID search, and older-format sessions fail to open

Environment

• Claude Code VS Code extension
• Versions observed: 2.1.81 (older session that now fails to open), 2.1.105, 2.1.114
• OS: Windows 11

Scale context (relevant to Bugs 1 & 2)

A single project's session store (.claude/projects/<slug>/) can accumulate a very large number of .jsonl files — easily thousands per week on active projects and, at the high end, 10,000+ sessions in one project directory. The picker's behavior degrades sharply in this regime: recent sessions cannot be found either by scrolling the list or by title search, even though they exist on disk and pass JSONL validation.

Reducing the project directory's file count (by archiving older .jsonl files to a sibling folder) makes the picker usable again — which strongly suggests the picker is either paginating / capping the returned list, sorting by something other than mtime, or doing an O(N) search that produces poor results at scale. Users should not have to GC their own session store for the picker to work.

Bug 1 — picker does not sort by mtime (or does not show recent sessions at scale)

Symptoms at ~10,000+ sessions in one project dir:

• Sessions modified within the last 15 minutes are not visible at the top of the picker.
• Scrolling the list does not reliably surface them — they appear to be interleaved with, or pushed off by, older sessions.
• No date / timestamp column is shown, so the ordering (whatever it is) is opaque.

Expected:

• Sort by mtime desc by default.
• Show a date/time column so users can verify the order and disambiguate similar-titled sessions.
• If the picker caps the result list, document the cap and still guarantee the N most-recent sessions are included.

Bug 2 — picker search matches title only; degrades at scale

Typing a session UUID (or UUID prefix) into the picker's search box returns "No sessions found" even when the session exists on disk at .claude/projects/<slug>/<uuid>.jsonl.

At scale this compounds Bug 1: if recent sessions can't be found by scrolling (because of sort/pagination), the only fallback is title search — but title search doesn't match UUIDs, and titles are commonly duplicated across sessions (re-running the same kind of work produces similar auto-generated titles), so a title query can easily return the wrong session.

Expected:

• Match on session ID prefix in addition to title.
• Display the UUID (at least a prefix) and the mtime next to each entry in the list, so even when titles collide the correct session can be picked.

Bug 3 — older-format sessions fail to open

Selecting a session recorded by an older extension version (observed: 2.1.81) from a current extension version (2.1.114) shows:

"The editor could not be opened due to an unexpected error. Please consult the log for more details."

with no additional detail in the editor. The underlying JSONL parses cleanly line-by-line and contains the expected ai-title, user, and assistant-type records, so the failure is in the extension's session loader rather than in the file.

Asks

1. Sort the picker by mtime desc by default; add a date/time column.
2. Include session UUID (at least a prefix) in the picker's search index and/or displayed entries.
3. Show a readable error (or forward-migrate older session formats) when loading an older session fails.
4. Document any cap the picker applies to the session list, and ensure the most-recent N are always included.