phase 8 step 4: web-ui login endpoint (pipes, no pty)

CLAUDE.md

@@ -249,9 +249,12 @@ See PLAN.md → "Phase 8" for the full design. Summary:
 - **Login from the per-agent web UI.** Spawn `claude /login` with plain
   stdio pipes (no PTY initially), surface the OAuth URL from stdout on the
   page, accept the resulting code via a paste field, write it to the process
-  stdin. On success, harness transitions out of "needs login" and enters the
-  turn loop. If pipes turn out to be insufficient (claude refuses without a
-  TTY, raw-mode input, ANSI-only output) we redo the backend with a PTY.
+  stdin. Once `~/.claude/` populates, the existing needs-login polling loop
+  flips state to Online and starts the turn loop — no separate signaling
+  needed. The exact command is overridable via `HYPERHIVE_LOGIN_CMD` so we
+  can adjust without rebuilding. If pipes turn out to be insufficient
+  (claude refuses without a TTY, raw-mode input, ANSI-only output) we redo
+  the backend with a PTY (e.g. `portable-pty`).
 
 Implementation order: bind-mount/dir creation → approval-gated spawn +
 spinner → "needs login" partial run → PTY login endpoint. The login UI has