feat(grok-cli): grok CLI agent image + headless entrypoint

The roboco-agent-grok image now installs xAI's official grok CLI (Grok Build,
pinned 0.2.56) instead of opencode, authenticated by the SuperGrok subscription
via a mounted ~/.grok/auth.json (parity with the Claude ~/.claude mount, no
metered API key). The entrypoint renders ~/.grok/config.toml + per-role flags
from /app (the ModuleNotFound-shadowing lesson), runs grok -p headless with
--output-format json, keeps the prompt-injection guard, and exits 75 on a
rate-limit so the orchestrator parks the provider. No in-container SDK server or
budget-feed — native --max-turns + server-side terminal-substitute replace them.

docker/scripts/grok-cli-agent-entrypoint.sh

@@ -0,0 +1,67 @@
+#!/usr/bin/env bash
+# Entrypoint for the roboco-agent-grok-cli image (one-shot delivery roles).
+#
+# Runs an agent on xAI's official `grok` CLI (Grok Build), authenticated by the
+# SuperGrok subscription via a mounted ~/.grok/auth.json — the parity analogue of
+# the Claude Code path's mounted ~/.claude. The gateway, identity, and workspace
+# are mounted by the orchestrator's shared container assembly (the same that
+# wires Claude); this entrypoint renders the grok runtime config from that mount
+# and runs the CLI headless.
+set -euo pipefail
+
+# Render ~/.grok/config.toml (the MCP gateway) + the per-role grok flags. Run
+# from /app so `python -m` resolves the INSTALLED roboco package: dev/doc/qa
+# agents run at their workspace-clone cwd, whose own roboco/ dir would shadow it
+# on the sys.path front (the ModuleNotFound lesson). The render reads
+# ROBOCO_MCP_CONFIG + ROBOCO_AGENT_ID and writes the config + an args file.
+( cd /app && python -m roboco.llm.providers.grok_cli_config )
+
+GROK_ARGS_FILE="${ROBOCO_GROK_ARGS_FILE:-/tmp/roboco-grok-args}"
+mapfile -t GROK_ARGS < "$GROK_ARGS_FILE"
+
+# Prompt-injection guard (parity with the Claude UserPromptSubmit hook): the task
+# prompt is DATA, not instructions — refuse a poisoned one before the model sees
+# it. Same patterns as docker/scripts/user-prompt-hook.sh; run from /app too.
+if ! ( cd /app && python -m roboco.agent_sdk.prompt_guard "${ROBOCO_INITIAL_PROMPT:-}" ); then
+  echo "Refusing to run: task prompt matched a prompt-injection pattern." >&2
+  exit 1
+fi
+
+# Run the agent. The prompt comes from an env var (never an untrusted argv
+# positional). `< /dev/null` keeps the headless run from blocking on stdin. We
+# do NOT `exec`: the script regains control to inspect the result + exit code.
+# `--cwd` is the agent's workspace (the orchestrator sets the container workdir
+# to it, mirroring the Claude path). Per-role flags (tool removal / deny rules /
+# effort / turn cap) come from the rendered args file.
+RUN_LOG="/tmp/grok-run.json"
+ERR_LOG="/tmp/grok-run.err"
+WORKSPACE="${ROBOCO_WORKSPACE:-$PWD}"
+set +e
+grok -p "${ROBOCO_INITIAL_PROMPT:-}" \
+  -m "${ROBOCO_AGENT_MODEL:-grok-build}" \
+  --cwd "$WORKSPACE" \
+  --output-format json \
+  "${GROK_ARGS[@]}" \
+  < /dev/null > "$RUN_LOG" 2> "$ERR_LOG"
+run_rc=$?
+set -e
+# Surface the run output + any stderr into the agent log.
+cat "$RUN_LOG"
+[ -s "$ERR_LOG" ] && cat "$ERR_LOG" >&2
+
+# Rate-limit detection (parity with the opencode B4 path): an xAI 429 / quota
+# error ends the run without a terminal verb. Detect it from the run output and
+# exit 75 (EX_TEMPFAIL) so the orchestrator PARKS the grok provider instead of
+# the dispatcher respawning the same task every tick (429 -> exit -> respawn, a
+# token loop). A rate-limited task is retried once the limit lifts, not dropped.
+if grep -qiE '(\b429\b|rate.?limit|too many requests|quota|insufficient_quota)' \
+    "$RUN_LOG" "$ERR_LOG" 2>/dev/null; then
+  echo "[grok] rate-limited — exiting 75 so the orchestrator parks the provider;" \
+    "the task is retried when the limit lifts." >&2
+  exit 75
+fi
+
+# A graceful exit without a terminal verb is handled server-side by the
+# orchestrator (_handle_stopped_container substitutes the still-owned task) —
+# the grok-cli runtime needs no in-container SDK server for that.
+exit "$run_rc"