test: add CLI backend image probe

docs/gateway/cli-backends.md

@@ -151,6 +151,8 @@ imageMode: "repeat"
 Clawdbot will write base64 images to temp files and pass their paths.
 If `imageArg` is missing and images are present, the CLI backend will fail fast
 (so fallback continues to the next provider).
+If your CLI does not expose an image flag (the current Claude CLI does not),
+leave `imageArg` unset and stick to text-only runs.
 
 ## Inputs / outputs
 

docs/testing.md

@@ -178,6 +178,9 @@ CLAWDBOT_LIVE_TEST=1 CLAWDBOT_LIVE_SETUP_TOKEN=1 CLAWDBOT_LIVE_SETUP_TOKEN_PROFI
   - `CLAWDBOT_LIVE_CLI_BACKEND_COMMAND="/full/path/to/claude"`
   - `CLAWDBOT_LIVE_CLI_BACKEND_ARGS='["-p","--output-format","json","--permission-mode","bypassPermissions"]'`
   - `CLAWDBOT_LIVE_CLI_BACKEND_CLEAR_ENV='["ANTHROPIC_API_KEY","ANTHROPIC_API_KEY_OLD"]'`
+  - `CLAWDBOT_LIVE_CLI_BACKEND_IMAGE_PROBE=1` to send a real image attachment (requires `CLAWDBOT_LIVE_CLI_BACKEND_IMAGE_ARG`).
+  - `CLAWDBOT_LIVE_CLI_BACKEND_IMAGE_ARG="--image"` to pass image file paths to the CLI.
+  - `CLAWDBOT_LIVE_CLI_BACKEND_IMAGE_MODE="repeat"` (or `"list"`) to control how image args are passed.
   - `CLAWDBOT_LIVE_CLI_BACKEND_DISABLE_MCP_CONFIG=0` to keep Claude CLI MCP config enabled (default disables MCP config with a temporary empty file).
 
 Example: