docs: session create examples use parameter names that don't exist in any SDK

[nibzard]

Summary

An external evaluation of agent traces flagged friction around session creation. Validating it against the OpenAPI spec (steel-main/apps/api/openapi/openapi.json) and all four SDK repos (steel-node, steel-python, steel-go, steel-rust) confirmed one large docs bug and a few smaller ones: 18 spots across 16 pages document a sessionTimeout / session_timeout parameter that exists in no SDK and not in the REST API.

The verified truth:

Surface	Session timeout param	Custom ID param
REST API / OpenAPI	timeout (default 300000 ms), inactivityTimeout	sessionId
steel-node	timeout	sessionId
steel-python	api_timeout (wire-aliased to timeout; timeout is reserved for the HTTP request timeout)	session_id
steel-go	Timeout	SessionID
steel-rust	timeout	session_id

Impact: the Python spelling raises TypeError: unexpected keyword argument; the TS spelling is a compile error under strict excess-property checks, or silently ignored in JS, so users get the 5-minute default and sessions die mid-run.

P0: replace the invented timeout parameter (18 spots)

Sync warning: scripts/sync-cookbook.ts regenerates content/docs/cookbook/ pages from the steel-cookbook recipe READMEs, and several of the bullets below mirror that upstream text. The steel-cookbook READMEs must be fixed first (or together with this), otherwise the next sync reintroduces the bug.

sessionTimeout → timeout (TypeScript context):

• content/docs/cookbook/trigger-dev-browser-job.mdx:26 (inside a code fence, the only executable occurrence)
• content/docs/cookbook/google-adk.mdx:107
• content/docs/cookbook/vercel-ai-sdk-nextjs.mdx:83
• content/docs/cookbook/mastra.mdx:102
• content/docs/cookbook/magnitude.mdx:114
• content/docs/cookbook/openai-agents.mdx:89
• content/docs/cookbook/playwright.mdx:73
• content/docs/cookbook/puppeteer.mdx:69
• content/docs/cookbook/vercel-ai-sdk.mdx:77
• content/docs/cookbook/credentials.mdx:86

session_timeout → api_timeout (Python context):

• content/docs/cookbook/selenium.mdx:91
• content/docs/cookbook/playwright.mdx:147
• content/docs/cookbook/stagehand.mdx:240
• content/docs/cookbook/notte.mdx:75
• content/docs/cookbook/agno.mdx:70
• content/docs/cookbook/credentials.mdx:169
• content/docs/cookbook/browser-use.mdx:66
• content/docs/cookbook/browser-use-captcha-auto.mdx:91

All 18 are prose bullets except trigger-dev-browser-job, which has it in real code.

P1: wrong-language and wrong-case snippets

• content/docs/changelog/changelog-015.mdx:20 and :52: fences labeled TypeScript contain Python bodies; the second snippet (StealthConfig={humanize_interactions=True}) is invalid syntax in both languages
• content/docs/changelog/changelog-018.mdx:25: TypeScript-labeled fence with a Python body (upload_from_store(url=...), extension_ids=[...])
• content/docs/changelog/changelog-019.mdx:26: Python-style # comment inside a TypeScript fence
• content/docs/overview/captchas-api/overview.mdx:65: Python example passes stealth_config={"autoCaptchaSolving": False}; the Python SDK TypedDict key is auto_captcha_solving
• content/docs/overview/stealth/captcha-solving.mdx:123: same autoCaptchaSolving casing bug in a Python fence

P2: document that session IDs are one-shot

• Add one sentence to the "Reserving a Session ID" section in content/docs/overview/sessions-api/session-lifecycle.mdx: recreating a session with a released session's ID returns a 409 Conflict ("Session with this sessionId already exists"), so generate a fresh UUID per session. The API already links to this page in that error, so the answer should be here when users land on it.

Acceptance criteria

• No occurrence of sessionTimeout or session_timeout remains in content/docs/
• Every session-create example compiles/runs against steel-node and steel-python current releases
• Changelog fences match their labeled language
• Lifecycle page states the ID-reuse constraint

Related findings, out of scope for this repo

• steel-cookbook: fix the session_timeout prose bullets in the recipe READMEs that sync-cookbook.ts pulls from (blocking for the P0 checklist above)
• steel-node: the published npm README references api.md twice but the file is not shipped in the package (Stainless config)

The evaluation report's product asks (lifecycle-aware errors, server-side trace visibility, steel init) are intentionally excluded; those belong in the API/platform tracker.