Simplify eagle-exec by using active instance file

Instead of querying nginx config on every invocation, deploy-blue-green.sh
now writes the active instance to /opt/eagle0/.active-instance.

eagle-exec reads this file directly, with a fallback to checking running
containers if the file doesn't exist.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

scripts/deploy-blue-green.sh

@@ -35,6 +35,7 @@ WARMUP_SCRIPT="${SCRIPT_DIR}/warmup-eagle.sh"
 SAVES_DIR="${APP_DIR}/saves"
 FLUSH_MARKER="${SAVES_DIR}/.flush_complete"
 DEPLOYMENT_IN_PROGRESS="${SAVES_DIR}/.deployment_in_progress"
+ACTIVE_INSTANCE_FILE="${APP_DIR}/.active-instance"
 
 # Colors for output
 RED='\033[0;31m'
@@ -298,6 +299,10 @@ main() {
     create_flush_marker "${deploy_id}" "eagle-${staging}"
     log_info "[DEPLOY:${deploy_id}] Flush marker created - server will auto-invalidate stale cache"
 
+    # Write active instance file for eagle-exec helper
+    echo "eagle-${staging}" > "${ACTIVE_INSTANCE_FILE}"
+    log_info "[DEPLOY:${deploy_id}] Active instance file updated: eagle-${staging}"
+
     # Update .env for admin service
     local env_file="${APP_DIR}/.env"
     if [ "$staging" = "green" ]; then

scripts/eagle-exec.sh

@@ -1,43 +1,32 @@
 #!/bin/bash
 #
 # Helper to run docker exec against the active Eagle instance.
-# Automatically determines whether blue or green is active based on nginx config.
+# Reads the active instance from /opt/eagle0/.active-instance (set by deploy-blue-green.sh).
 #
 # Usage:
-#   ./scripts/eagle-exec.sh printenv GEMINI_API_KEY
-#   ./scripts/eagle-exec.sh jcmd 1 VM.flags
-#   ./scripts/eagle-exec.sh sh    # Get a shell
-#
-# Or create an alias:
-#   alias eagle-exec='/opt/eagle0/scripts/eagle-exec.sh'
+#   eagle-exec printenv GEMINI_API_KEY
+#   eagle-exec jcmd 1 VM.flags
+#   eagle-exec sh    # Get a shell
 #
 
 set -euo pipefail
 
 APP_DIR="${APP_DIR:-/opt/eagle0}"
+ACTIVE_FILE="${APP_DIR}/.active-instance"
 
-# Determine active instance from nginx config
-get_active_instance() {
-    local backend
-    backend=$(docker exec nginx grep -o 'eagle-[a-z]*:40032' /etc/nginx/nginx.conf 2>/dev/null | head -1 || echo "")
-
-    if [ "$backend" = "eagle-blue:40032" ]; then
-        echo "eagle-blue"
-    elif [ "$backend" = "eagle-green:40032" ]; then
-        echo "eagle-green"
+# Read active instance from file, with fallback
+if [ -f "$ACTIVE_FILE" ]; then
+    ACTIVE=$(cat "$ACTIVE_FILE")
+else
+    # Fallback: check which container is actually running
+    if docker inspect --format='{{.State.Running}}' eagle-blue 2>/dev/null | grep -q true; then
+        ACTIVE="eagle-blue"
+    elif docker inspect --format='{{.State.Running}}' eagle-green 2>/dev/null | grep -q true; then
+        ACTIVE="eagle-green"
     else
-        # Fallback: check which container is actually running
-        if docker inspect --format='{{.State.Running}}' eagle-blue 2>/dev/null | grep -q true; then
-            echo "eagle-blue"
-        elif docker inspect --format='{{.State.Running}}' eagle-green 2>/dev/null | grep -q true; then
-            echo "eagle-green"
-        else
-            echo ""
-        fi
+        ACTIVE=""
     fi
-}
-
-ACTIVE=$(get_active_instance)
+fi
 
 if [ -z "$ACTIVE" ]; then
     echo "Error: No active Eagle instance found" >&2