Grok 1.0.13 moved session storage to SQLite — file-based discovery and transcript backfill are dead

[wxtsky]

Found while investigating #318. Grok shipped 1.0.13 (from the 0.2.x line) and replaced its on-disk session layout. Everything in AppState that reads Grok sessions from the filesystem now finds nothing.

What changed

Before (0.2.x):

~/.grok/sessions/<percent-encoded-cwd>/<session-uuid>/
    chat_history.jsonl
    summary.json
    events.jsonl
    updates.jsonl

After (1.0.13) — the whole tree is gone, replaced by a single index:

~/.grok/sessions/session_search.sqlite

CREATE TABLE session_docs (
    session_id   TEXT PRIMARY KEY,
    cwd          TEXT NOT NULL,       -- plain path, no percent-encoding
    updated_at   INTEGER NOT NULL,    -- unix seconds
    title        TEXT NOT NULL,
    content      TEXT NOT NULL,       -- flattened digest, not a transcript
    content_hash TEXT NOT NULL
);

plus an FTS5 mirror (session_docs_fts). meta holds session_search_schema_version = 4. The migration also drops empty ~/.grok/relocations/<session-id>.lock markers.

Verified locally: grok --version → grok 1.0.13 (5e9a58528b76) [stable], ~/.grok/sessions/ contains only the SQLite file, and find ~/.grok -name chat_history.jsonl returns nothing.

What breaks

All in Sources/CodeIsland/AppState.swift:

• grokSessionCandidates(cwd:) walks ~/.grok/sessions/<encoded-cwd>/ → always empty, so findActiveGrokSessions returns nothing and matchGrokSessionsToProcesses has nothing to match.
• grokEncodedCwd — 1.0.13 stores the plain path in a column; the percent-encoded directory name no longer exists.
• transcriptPath points at chat_history.jsonl, so message backfill and the transcript tailer are dead.
• The ("grok", "\(ConfigInstaller.grokHome())/sessions") watch now only fires when the SQLite index is rewritten.

Hooks are unaffected — they run out of ~/.grok/hooks/codeisland.json and don't touch session storage — so Grok cards still appear and still update. What's lost is everything discovery adds on top: recovering a session CodeIsland didn't see start, backfilling recent messages, and reattaching after a CodeIsland restart.

Notes for the fix

• session_docs has no created_at, only updated_at. grokSessionProcessMatchScore leans on createdAt for its ±120s window and for the resumed-session branch, so the scoring needs rethinking rather than a straight port.
• content is a flattened digest (title + a run of text and tool names), not turn-structured — usable for a preview line, not as a transcript source.
• Both layouts will be in the wild for a while, so detection should be by what's on disk (SQLite present vs. cwd directories present) rather than by a version probe.
• Reading the index while Grok is running means opening the SQLite read-only, and ideally in WAL-safe fashion, since Grok writes it live.

Filing rather than fixing because I have no live 1.0.13 session to verify against — the scoring change in particular needs a real session to test, and guessing at it risks hiding sessions that currently work via hooks.