fix(docs): correct beads-rust reference + stale "SQLite data model" claim

README.md

@@ -1,7 +1,7 @@
 # Project Board — coding orchestration plugin
 
 A **protoAgent plugin** that turns an idea into merged PRs: a lean 6-state board
-backed by [beads](https://github.com/steveyegge/beads) (`br`), an **ACP spawn loop**
+backed by [beads-rust](https://github.com/Dicklesworthstone/beads_rust) (`br`), an **ACP spawn loop**
 that dispatches a coding agent per feature into an isolated git worktree, an
 adversarial **planning layer**, and a Kanban/list **console view**.
 
@@ -57,7 +57,10 @@ spawn primitive — it does not reimplement it.
 ## Requirements
 
 - **protoAgent ≥ 0.27.0** (console views + the ACP delegate teardown).
-- The **`br`** (beads) CLI on `PATH` — the board's DAG/status store.
+- **beads-rust** — the **`br`** CLI on `PATH`, the board's DAG/status store. Install
+  with `cargo install beads_rust`. NOT the stale homebrew `bd` (a different, write-
+  broken package); the `bd-`/`br-` prefix in issue ids is just the workspace
+  namespace. Override the binary with `BR_BIN` if needed.
 - `git` + the **`gh`** CLI (authenticated) for branch push + PR creation.
 - The **`delegates`** plugin enabled, with an **`acp`** coder delegate declared
   (e.g. `proto`). A reviewer `a2a` delegate is optional (review dispatch is off by

__init__.py

@@ -1,8 +1,10 @@
 """project_board — lean 6-state coding board + ACP spawn loop.
 
-Composition over construction: the board is a SQLite data model + an HTTP API +
-the orchestration loop, and the loop dispatches through the already-built
-``delegates`` plugin (ADR 0024/0025) — it does NOT reimplement the spawn primitive.
+Composition over construction: the board is a **projection over beads** (`br`) — no
+separate store of its own (store.py shells the `br` CLI; beads owns the `.beads/*.db`
++ JSONL) — plus an HTTP API and the orchestration loop, which dispatches through the
+already-built ``delegates`` plugin (ADR 0024/0025) — it does NOT reimplement the
+spawn primitive.
 
 Reach used (no core edits): ``register_router`` (the board API), ``register_surface``
 (the background puller), ``register_tool`` (board ops the agent can drive headlessly).

store.py

@@ -67,7 +67,10 @@ class BeadsBoard:
 
     def __init__(self, db: str | None = None, actor: str = "agent", repo: str = ".", base_branch: str = "main"):
         if not shutil.which(BR):
-            raise BoardError(f"beads CLI {BR!r} not on PATH — install beads or set BR_BIN")
+            raise BoardError(
+                f"beads CLI {BR!r} not on PATH — install beads-rust (`cargo install beads_rust`), "
+                "not the homebrew `bd`, or set BR_BIN"
+            )
         self.db = db or None
         self.actor = actor
         self.repo = repo