#Captures

@capture <scope> <name> <expression> evaluates after the response arrives and stores the result for reuse.

Captures run in declaration order. A capture can read values produced earlier in the same batch through vars.get, {{= ... }}, or {{name}}. Values are stored only after every capture succeeds, so a failed batch leaves request, file, and global values unchanged.

Expressions can reference:

• response.statusCode, response.statusText, response.text()
• response.headers["header-name"] or response.header("Header-Name") for a single-valued header
• response.json.path shorthand (equivalent to response.json().path)
• stream.kind(), stream.summary().sentCount, stream.summary().dropped, and stream.events()[0].text for streaming transcripts (available when the request used @sse or @websocket). A non-zero dropped value means the retained transcript is incomplete.
• vars.*, env.*, last.*, imported @use modules, and other RestermScript helpers

Example:

### Seed session
# @name AnalyticsSeedSession
# @capture global-secret analytics.sessionToken = response.json.sessionToken
# @capture file analytics.lastJobId = response.json.jobId
# @capture request analytics.trace = response.header("x-amzn-trace-id")
POST https://httpbin.org/anything/analytics/sessions

Template captures such as {{response.json.token}} remain supported and can be used alongside RTS capture expressions.

@capture treats a value with a complete, unquoted {{...}} marker as interpolated text. Otherwise it parses the value as RestermScript. In text mode, surrounding characters such as # and unmatched brackets are literal. In script mode, # starts a comment.

An unquoted marker in a script comment switches the capture to text mode. Resterm warns when the remaining text looks like a function call, but it cannot reliably detect every case. Quote markers mentioned in comments:

# @capture request x response.statusCode # mention "{{token}}"

Set # @setting capture.strict true to make capture-path misses fail instead of silently resolving to an empty string.

Do not mix unquoted template markers and RTS call syntax in the same capture expression (for example contains({{name}}, "x")). Use pure RTS (contains(vars.get("name") ?? "", "x")) or a template expression ({{= contains(...) }}).

capture.strict is the canonical key. capture-strict and capture_strict are accepted for compatibility. When multiple aliases are present, precedence is capture.strict > capture-strict > capture_strict.