/')","sourceCodeStart":2500,"sourceCodeEnd":2536,"githubUrl":"https://github.com/jackwener/OpenCLI/blob/49907e53dc3ade5c223ff0c4c2c2785687cec4e6/src/cli.ts#L2500-L2536","documentation":"The `browser eval` command with a `--frame ` option requires `page.evaluateInFrame` to run JavaScript inside a specific iframe. When the backend does not implement frame-targeted evaluation, this capability error is thrown instead of silently evaluating in the wrong context.","triggerScenarios":"Running `browser eval --frame 2` (or similar frame option) where `page.evaluateInFrame` is undefined; frame index validity is checked first, so this fires only when the index is a valid non-negative integer but the backend lacks the feature.","commonSituations":"Minimal/CDP-lite drivers without frame execution support; cross-origin iframes the driver cannot reach; older adapter versions before evaluateInFrame was added.","solutions":["Use a backend implementing evaluateInFrame (Playwright/Puppeteer with frame support).","Run the script without `--frame` and target the iframe's contentWindow from the main world via `browser eval` where same-origin.","Get a frame handle differently, e.g. enumerate frames with `browser frames` and use backend-specific frame APIs."],"exampleFix":"// before\nbrowser --backend minimal eval \"document.title\" --frame 0\n// after\nbrowser --backend playwright eval \"document.title\" --frame 0","handlingStrategy":"type-guard","validationCode":"const frameIndex = Number(opts.frame);\nconst page = await getBrowserPage();\nif (Number.isInteger(frameIndex) && frameIndex >= 0 && typeof page.evaluateInFrame !== 'function') {\n throw new Error('Backend lacks frame-targeted evaluation; drop --frame or switch backends');\n}","typeGuard":"function supportsFrameEval(page) {\n return typeof page?.evaluateInFrame === 'function';\n}","tryCatchPattern":"try {\n await run(['browser', 'eval', js, '--frame', String(i)]);\n} catch (err) {\n if (String(err.message).includes('frame-targeted evaluation')) {\n await run(['browser', 'eval', `(()=>{const f=document.querySelectorAll('iframe')[${i}];return f.contentDocument.title})()`]);\n } else throw err;\n}","preventionTips":["Only pass --frame when the backend implements evaluateInFrame.","Check same-origin access to iframes before evaluating inside them.","Use `browser frames` to confirm the index exists.","Fall back to main-world contentWindow access for same-origin frames."],"tags":["browser","cli","capability","iframe"],"backgroundTag":"unsupported-browser-capability","analyzedSha":"49907e53dc3ade5c223ff0c4c2c2785687cec4e6","analyzedAt":"2026-08-29T08:14:47.543Z","schemaVersion":2},"datasetVersion":"2026-08-29T12:17:43.993Z"}