docs: drop ring buffer mentions from ws spec and plan

Co-Authored-By: Claude <noreply@anthropic.com>

docs/superpowers/specs/2026-07-03-terminal-websocket-design.md

@@ -25,9 +25,9 @@ path.
   directions are text frames carrying raw bytes (UTF-8). We do not use a
   custom envelope or JSON framing in v1.
 - Backend process model gets two new responsibilities: capture child
-  stdout/stderr into an in-memory ring buffer plus a list of subscriber
-  channels, and accept stdin writes. This stays inside `internal/process`;
-  the API layer is a thin WebSocket adapter.
+  stdout/stderr into a list of subscriber channels, and accept stdin
+  writes. This stays inside `internal/process`; the API layer is a thin
+  WebSocket adapter.
 - The existing `Manager` interface grows one method: `Subscribe(workspaceID)
   (Subscription, error)`. We also add an `Input` accessor on the service
   layer for stdin. The surface stays small.
@@ -61,14 +61,13 @@ path.
     Buffered to a small constant (e.g. 32) to avoid blocking the producer.
   - `Close() error` — drops the subscription. Idempotent.
 - `LocalManager` keeps per-session:
-  - a `bytes.Buffer` of recent output (cap, e.g. 64 KiB) for any future
-    replay — implemented but **not exposed in v1**.
-  - a `[]chan []byte` of subscribers, guarded by `sync.Mutex`.
+  - a `map[Subscription]struct{}` of subscribers, guarded by `sync.Mutex`.
   - a `io.WriteCloser` for stdin (created via `cmd.Stdin = ...`).
 - On `Start`, set `cmd.Stdout` and `cmd.Stderr` to a pipe. A new goroutine
-  per session reads from the pipe, writes to the ring buffer, and fans out
-  to every subscriber channel. A non-blocking send (`select` with
-  `default`) drops output for slow clients. A 4 KiB read buffer is fine.
+  per session reads from the pipe and fans out to every subscriber channel.
+  A non-blocking send (`select` with `default`) drops output for slow
+  clients. A 4 KiB read buffer is fine. Replay of past output is **not** in
+  v1; a future task can add a ring buffer behind a separate accessor.
 - `Wait()` is called in a separate goroutine; on exit, the manager closes
   all subscriber channels and stores the exit status on the session.
 
@@ -196,9 +195,6 @@ path.
 
 - The `Subscription` type and the `Input` writer are the two new
   capabilities the manager must grow. They are small and orthogonal.
-- The ring buffer for replay is implemented but unused in v1. This is
-  dead weight. **Defer**: the spec keeps it for symmetry with future
-  replay work. Plan may drop it if not needed.
 - The exit banner format (`\r\n[process exited with code N]\r\n`) is a
   simple, debuggable string. We are not building a structured protocol.
 - All v1 design decisions aim to keep the backend diff small, the