Browser API lacks supported document/session identity for detecting same-tab reload/navigation

What variant of Codex are you using?

Codex App on macOS with the official OpenAI Chrome extension

What feature would you like to see?

Problem

Codex browser workflows expose a stable tab identity, but I could not find a supported document/session identity that changes when the same tab reloads, navigates, or replaces its current document.

This creates an observability gap for fail-closed governed browser workflows.

Why it matters

A workflow can prove it is still using the same tab, but cannot prove that the document/session inside that tab has not been replaced between an authorization boundary and prompt submission.

URL, title, DOM state, composer state, and conversation identifiers are not sufficient for this.

Requested capability

A supported, read-only document/session identifier that:

• is stable for the current document/session;
• changes on reload, navigation, or document replacement;
• can be observed together with the existing tab identity;
• is not caller-supplied or forgeable.

An opaque cross-browser identifier would be sufficient; it does not need to expose Chrome-specific internals.

Environment

• Codex App on macOS
• official OpenAI Chrome extension
• stable tab ID available
• no supported current-document/session identity found

This currently blocks a fail-closed governed browser workflow before model interaction.

Additional information

No response

The issue names no files, tests, or entry points. Begin by tracing the existing supported tab identity in the Codex App and official Chrome extension, then check how reload, navigation, and document replacement are represented. Done means a supported, read-only, non-forgeable document/session identity is exposed alongside tab identity and covered for those transitions.