fix(minimax,z-ai): write apiKeyHelper to agent home, mode 0444 for read

Mirrors agent-runtimes commit 166c19b. CRS serves these harness files to
dispatchers, so this repo must match.

Two fixes from the failing smoke test:

1. init.sh resolves the agent user's home via getent (init.sh runs as
   root, but claude runs as the agent user — different $HOME).
2. secrets_required mode "0400" → "0444" so the agent user can read the
   ESO-mounted secret via apiKeyHelper. The file is in pod-local tmpfs.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

harnesses/contexts/minimax/v1/harness.yaml

@@ -18,7 +18,12 @@ secrets_required:
   - name: minimax
     account_ref: "minimax"
     mount_path: /run/agent/secrets/minimax
-    mode: "0400"
+    # 0444 — readable by the agent user that runs `claude` (and thus
+    # apiKeyHelper). The pod has no fsGroup, so the kubelet mounts the
+    # secret as root:root; mode 0400 would block the legitimate read.
+    # The file lives in pod-local tmpfs — "world readable" only means
+    # readable by other processes in this same pod, which we control.
+    mode: "0444"
 
 scripts:
   init: ./init.sh

harnesses/contexts/minimax/v1/init.sh

@@ -27,11 +27,21 @@ if [ ! -r "$API_KEY_FILE" ]; then
     exit 1
 fi
 
-# Resolve the agent's home and write settings.json there. CLAUDE_CONFIG_DIR
-# overrides ~/.claude when set; honour it so non-default profiles work.
-CONFIG_DIR="${CLAUDE_CONFIG_DIR:-$HOME/.claude}"
+# init.sh runs as root in uid-wrapper.sh BEFORE gosu drops privileges to the
+# agent user — so $HOME here is /root, not the agent home. Claude Code will
+# run as the agent user and read its config from $AGENT_HOME/.claude. Resolve
+# the agent home explicitly so settings.json lands where claude looks.
+AGENT_USER="${AGENT_USER:-agent}"
+AGENT_HOME=$(getent passwd "$AGENT_USER" | cut -d: -f6)
+if [ -z "$AGENT_HOME" ] || [ ! -d "$AGENT_HOME" ]; then
+    AGENT_HOME="/home/$AGENT_USER"
+fi
+
+# CLAUDE_CONFIG_DIR overrides ~/.claude when set.
+CONFIG_DIR="${CLAUDE_CONFIG_DIR:-$AGENT_HOME/.claude}"
 mkdir -p "$CONFIG_DIR"
-chmod 0700 "$CONFIG_DIR"
+chown "$AGENT_USER:" "$CONFIG_DIR" 2>/dev/null || true
+chmod 0755 "$CONFIG_DIR"
 
 SETTINGS_FILE="$CONFIG_DIR/settings.json"
 
@@ -52,5 +62,8 @@ else
 EOF
 fi
 
-chmod 0600 "$SETTINGS_FILE"
-echo "minimax api_key wired via apiKeyHelper at $SETTINGS_FILE"
+# settings.json holds the helper command (a path), not a credential value.
+# It must be readable by the agent user that runs claude.
+chown "$AGENT_USER:" "$SETTINGS_FILE" 2>/dev/null || true
+chmod 0644 "$SETTINGS_FILE"
+echo "minimax api_key wired via apiKeyHelper at $SETTINGS_FILE (agent_user=$AGENT_USER)"