B6: waterfall direction toggle (v0.19.2)

NEW/OLD button toggles between newest-first and oldest-first ordering.
scrollToTop() replaced by scrollToLatest() which checks direction.
appendMessage() uses prepend/append based on direction.
Preference persisted in localStorage.

AGENTS.md

@@ -138,6 +138,7 @@ All streaming endpoints yield `data: {json}\n\n`. Key shapes:
 ### Completed this session
 - **B7 (v0.19.0)** — Apple Silicon worker support. `gpu.py` now detects `sys.platform == "darwin"` and parses `system_profiler SPDisplaysDataType` for GPU model/VRAM instead of `rocm-smi`. `hardware.py` has darwin branch via `_get_vram_darwin()`. `node_agent/agent.py` reports VRAM on macOS via `system_profiler`. 5 new tests cover linux/darwin gpu paths, 3 new hardware tests cover darwin assessment + VRAM parsing.
 - **B5 (v0.19.1)** — Default model auto-pull on first start. `model_pull.py` with `ensure_model()` checks llama-server availability, falls back to Ollama pull API. Integrated into `app.py` lifespan. 11 tests cover all paths.
+- **B6 (v0.19.2)** — Waterfall direction toggle. NEW/OLD topbar button toggles between newest-first and oldest-first ordering. `scrollToTop()` replaced by `scrollToLatest()` which checks direction. Preference persisted in localStorage.
 - **Scroll-position fighting** — `scrollToTop()` now respects `_userScrolledAway` flag (100px threshold), skips auto-scroll when user is reading older content. `resetScrollLock()` called on new messages.
 - **401 error cascade** — `SESSION_TIMEOUT_SECONDS` bumped 90→3600 (1 hour). All 10 unprotected `authFetch` calls wrapped in try/catch.
 - **Token counter** — removed localStorage persistence; resets to 0 on page refresh.
@@ -157,13 +158,12 @@ All streaming endpoints yield `data: {json}\n\n`. Key shapes:
 
 ### Upcoming (backlog)
 - B4 — RAG Corpus Management UI
-- B6 — waterfall direction toggle
 - B8 — **Encryption & PHI readiness** — spec out encryption at rest (SQLCipher for caic.db, Qdrant payload encryption) and in-transit (TLS for inference, AMQP, RAG). Per-user auth, audit logging, log sanitizer, data lifecycle. Document the "personal LAN HIPAA gap."
   - **Preferred approach: Private Chat mode** — a toggle that skips DB persistence, memory/RAG injection, content logging, and **external SearXNG searching** entirely. Zero stored data, zero external queries = zero data to protect. Simpler, more robust, less code to audit than full encryption. Design this as the primary PHI path before reaching for crypto.
   - **In-transit still needs TLS** — Private Chat eliminates at-rest risk, but AMQP (RabbitMQ) and inference (llama-server) traffic between coordinator and workers is still plaintext on the wire. TLS termination on each node is the lightweight fix (self-signed CA, nginx sidecar or RabbitMQ TLS).
 
 ### Key config values (current)
-- `VERSION = "v0.19.1"` in `config.py`
+- `VERSION = "v0.19.2"` in `config.py`
 - `SESSION_TIMEOUT_SECONDS = 3600`
 - `DEFAULT_MODEL = "qwen2.5-7b-instruct"`
 - `LLAMA_SERVER_BASE = "http://192.168.50.108:8081"`