rea/docs/website-script-export.md

Captured website scripts and static JavaScript analysis

export_web_scripts bridges retained browser sources into the existing local JavaScript analyzer. Both CLI and MCP use the same workflow. It reads a saved inspect_web_page or capture_browser_scenario capture and writes scripts plus a verified manifest into one caller-selected, absent directory.

Capture and export

For passive inspection, select include_script_sources: true (CLI: --include-script-sources). For scenarios, select capture.network.response_body: true. Save either the complete Evidence record or its normalized result as UTF-8 JSON. MCP structuredContent contains the complete Evidence record.

The capture must be a regular file. A symlink to a regular file is accepted; directories, named pipes and device files are rejected before reading capture bytes or creating output.

rea export-web-scripts /analysis/capture.json /analysis/exported-scripts --json
rea analyze-javascript-application /analysis/exported-scripts/files --json

MCP uses export_web_scripts with capture_path and output_directory absolute filesystem paths. Its inline result includes analysis_input, which can be passed directly to analyze_javascript_application. When no script bytes are exportable, analysis_input is null and the manifest retains the unavailable sources and their reasons. Capture again with the corresponding content option.

The destination must not exist. Use a new directory for each capture; an existing directory or symlink is rejected without overwriting its contents. REA creates private output, verifies every written file by digest and durable readback, and removes its own partial output on failure or cancellation. A failed rollback reports residual paths.

Sources and mappings

Every source is returned inline with its URL and its script/frame identity or request transaction and event sequence references. The result also contains the input capture's byte digest, original coverage, source Evidence link when provided, and the persisted manifest's digest and byte count. A saved Evidence envelope must have a valid semantic identifier and matching operation.

Exported relative_path values are relative to analysis_input.input_path. The persisted manifest.json contains the same inline manifest fields, excluding its own descriptor. It does not duplicate script bytes.

• Passive sources are the Debugger-exposed text encoded as UTF-8, with the verified source digest and source-map declaration retained. Unavailable or explicitly non-JavaScript sources remain unavailable.
• Scenario sources use observed requests classified as script, matched to completed response bytes by transaction and event identity. URLs never select the response. Binary and empty retained bytes are written exactly.
• Ordinary query-free .js, .mjs, and .cjs URL paths are arranged under a directory for each origin, preserving their relative module layout when it is unambiguous.
• Competing versions, query/fragment variants, case and file/directory prefix collisions, inline sources, and unrepresentable paths use unique isolated names with a stated reason. Missing competing sources also prevent selection of an apparently canonical version.

Interpretation and limits

Export does not fetch URLs or execute JavaScript. Retained Debugger sources and response bytes do not establish execution or a complete website. Response bytes are browser-decoded bytes; they do not represent transfer encoding. Declared redaction is preserved and can change JavaScript syntax; passive captures do not report a byte-redaction flag, so that value remains unknown.

The existing analyzer inventories and parses the actual exported files. It can resolve ordinary captured relative modules, but does not implement browser import maps, root-relative URL loading, remote imports, or runtime behavior. Its local resolver may strip import queries/fragments; isolated variants are kept away from canonical paths to prevent those from selecting a different observed version. Missing dependencies remain unknown. Source maps are not fetched or reconstructed during export.

The export Evidence describes a derivation from the saved capture. Subsequent application-analysis Evidence describes the local exported artifact. Their identities and authorities remain separate.

Verification

npm run verify:browser:scripts exercises active capture, exact source export, manifest readback, query variants, and relative-module analysis through a real browser, CLI, and stdio MCP. Set REA_BROWSER_EXECUTABLE to an installed Chrome-family browser. The verifier accepts an optional installed REA entrypoint argument for package verification. npm run verify:browser additionally covers passive inspect_web_page export through both public adapters.