feat(#6): startup session picker for bare TUI mode

v1 coverage-audit slice b2. The audit found list_sessions had no
caller — the startup session picker (design-brief §4) was never built;
bare TUI mode was a hard usage error. Add SessionPickerApp (mirrors
AgentPickerApp) and resolve bare mode in _resolve_then_run.

- Bare TUI mode (no --session/--new) now valid → session picker.
  Resolution: 0 sessions -> [no_sessions] exit 14 (resume-only per
  §4 "no in-app creation, --new only"); exactly 1 -> auto-resume
  (§4 "picker only when >1"); >=2 -> SessionPickerApp -> resume pick
  (Esc/Ctrl-D -> exit 0).
- cli._parse: bare TUI valid; --send still requires one flag; --agent
  forbidden in bare mode. run_tui PRE-002 xor -> mutually-exclusive.
- Contract #6 amended (SessionPickerApp + bare-mode resolution) +
  validated. TDD: 3 picker pilot tests + 5 resolution tests + 3 cli
  validation tests. Suite 528 green; touched code ruff-clean.

Design note: bare + 0 sessions errors (honors §4's no-in-app-creation
clause); the friendlier auto-fall-through-to-new is deferred pending
operator preference.

persistent-memory.md

@@ -151,6 +151,8 @@ decision. Captures rationale that won't be obvious from code alone.
 - `[2026-06-30]` **(b) Tier-1 frontier SCOPED, ready for a contract-first TDD cycle (next focused work).** The primitives already exist + are contracted + tested; the gap is PRESENTER-level wiring. Two slices: **(b1) SSE-resume** — contract #1 (`ratatoskr.sse_client`) DELIBERATELY makes resume caller-owned ("on `SseConnectionDropped`, the caller MAY invoke `reconnect_turn`"); `reconnect_turn` (sse_client.py:524) has NO caller. Gap = a SHARED resume-orchestration wrapper (catch `SseConnectionDropped` → track last-seen `sse_id` → `reconnect_turn` → continue), consumed by all 3 presenters per design-brief §8b "share the consumer, branch the presenter" (NOT per-presenter — that forks the consumer). New function block → **amend contract #1** (additive FN, e.g. `stream_turn_resilient`) then TDD (RED: drop-mid-stream→resume continuity; GREEN: wrapper; wire `cli --send` first as the tracer). Resume design pre-locked: in-process Last-Event-ID only, cross-process deferred to v2 (design-brief §8d). **(b2) session-picker** — `list_sessions` (sessions.py:198) has NO caller; add a Textual DataTable startup picker (>1 session) + `--session <id>`/`--new` CLI flags (design-brief §4, decisions pre-locked). Both pre-locked → heid-contract-review likely skippable as ceremony (small additive amendments to mature specs); heid-code-review still valuable. **#11 AdminEvents stays BLOCKED** on `admin.events.read` scope (infra-ops).
 - `[2026-06-30]` **(b1) SSE-resume SHIPPED (`v0.18.5`) — `stream_turn_resilient` (sse_client.py).** The shared resume-orchestration surface (design-brief §8b): wraps `stream_turn`+`reconnect_turn`, catches `SseConnectionDropped` (mid-stream drop OR clean-EOF-before-terminal) → resumes from last-seen `sse_id` via `reconnect_turn` (Last-Event-ID), up to `max_reconnects` (default 5); non-drop reconnect failures (412/410/400/TurnIdFlip/SseConnectFailed) PROPAGATE per contract #1's "surface, not recover". `last_seen` persists ACROSS attempts (a zero-event reconnect drop falls back to the prior attempt's id). Direct in-session TDD against a contract-#1 amendment (8 cases incl. two-drops, max-reconnects-exhausted, zero-budget, buffer-expired-propagates, unresumable-zero-event). Wired ALL THREE presenters through it (`v0.18.6`): `cli --send` (`cli.py:396`), TUI (`tui.py:1321`), web (`web/server.py:294`) — each a name-for-name `stream_turn`→`stream_turn_resilient` swap (the §8b "all presenters share the consumer" promise, fully kept; the TUI is the primary resume beneficiary — long-lived sessions / laptop-suspend). Suite 518 green; ruff+mypy clean on touched code (pre-existing cli.py:400/543 mypy warts left untouched per surgical rule); contract #1 validates OK. **heid-code-review NOT run** (small additive well-TDD'd wrapper; offered to operator). **b2 (session-picker + `--session`/`--new` flags) still pending.**
 
+- `[2026-06-30]` **(b2) session-picker SHIPPED (`v0.18.7`) — bare TUI mode → startup picker (design-brief §4).** `list_sessions` had NO caller; now bare TUI mode (no `--session`/`--new`) resolves via `list_sessions` in `_resolve_then_run`: **0 sessions → `[no_sessions]` error, exit 14** (resume-only, honors §4 "no in-app session creation — `--new` flag only"); **exactly 1 → auto-resume** (§4 "picker only when >1"); **≥2 → new `SessionPickerApp`** (Textual `App[str|None]`, mirrors `AgentPickerApp`; ListView of sessions) → resume the pick (Esc/Ctrl-D → exit 0). cli `_parse` relaxed: bare TUI now VALID (was "pass exactly one" error); `--send` still requires one flag (non-interactive, no picker); `--agent` forbidden in bare mode; `run_tui` PRE-002 XOR→"not both". Direct in-session TDD (contract #6 amendment, validated OK): 3 widget pilot tests + 5 `_resolve_then_run` resolution tests + 3 cli validation tests. Suite **528 green**; touched code ruff-clean (mypy: only the `BINDINGS` list-invariance warning every App in tui.py already carries — consistent). **DESIGN NOTE — bare+0-sessions → error (clause-consistent). The friendlier auto-fall-through-to-new alternative is DEFERRED pending operator preference (it would create a session without `--new`, against the §4 negative clause).** **Frontier now: `GET /capabilities`+`GET /me` → BifrostState/Tools widgets (`GET /admin/sessions/{id}/{bifrost,tools}`, admin-key) → #11 AdminEvents (BLOCKED on `admin.events.read`).** heid-code-review NOT run on b1 or b2 (offered).
+
 _41 older entries (2026-05-* — the original debug-TUI/web build era) archived to archival-memory.md._
 
 _For per-issue TDD implementation notes, Volva findings, and contract amendments, see the git log — every per-issue commit carries a structured message capturing the trail._