How to use GPT-5.5 Pro with a signed-in browser

GPT-5.5 Pro can help reason through a web research task, but it does not automatically inherit your browser or its login. To work with a signed-in site, choose a client that can run local tools, connect it to Tabbit CLI, and keep the target account signed in inside Tabbit Browser. A separate task tab lets the agent gather sources while you keep browsing. This guide uses a source-linked research brief as the example; it does not claim an external agent integration has been tested.

OpenAI's current API model page lists gpt-5.5-pro and the snapshot gpt-5.5-pro-2026-04-23. It describes Pro requests as Responses API requests, including Batch, and warns some may take several minutes. On October 14, OpenAI retired GPT-5.5 from ChatGPT, ChatGPT Work, and Codex, while stating that API access was unaffected. These are separate availability questions. (model page, release notes)

Key takeaways

• Treat GPT-5.5 Pro, the agent client, Tabbit CLI, and the logged-in browser as four separate pieces.

• OpenAI currently documents Pro for the Responses API. Do not assume Chat Completions compatibility or a client dropdown entry.

• Install Tabbit Browser and its local CLI. Verify the client can discover the Tabbit skill and that the CLI launcher can reach the intended browser.

• The existing sign-in can be reused when the CLI targets that same Tabbit environment. The agent gets a task tab; you retain the rest of the browser.

• Review the source URLs and draft before using or sharing the brief. Keep consequential actions under human control.

The setup at a glance

First verify the model path

The OpenAI model page currently names the API alias gpt-5.5-pro and snapshot gpt-5.5-pro-2026-04-23. It says Pro uses more compute, supports medium, high, and xhigh reasoning effort, and may take minutes. The same page limits GPT-5.5 Pro to Responses API requests, including Batch. It does not document Chat Completions compatibility for Pro. OpenAI's general endpoint listings are not a substitute for model-specific compatibility.

The API model is also not a ChatGPT plan label. The October 14 release note retires GPT-5.5 across ChatGPT, Work, and Codex but explicitly leaves API access unaffected. Check project permissions and current documentation at setup time. The listed model identifier does not guarantee that a third-party harness exposes it.

For the other family member's workflow, see how GPT-5.5 uses a browser to compare records. The GPT-5.5 overview covers the model itself, not this local-browser procedure.

Connect a local client to Tabbit

Install Tabbit Browser and the supported Tabbit CLI using the Tabbit CLI quick start. Then check three independent things: whether your agent client can use the model, whether the client can discover the Tabbit skill, and whether the installed CLI can reach the browser instance you mean to use.

Skill invocation varies by client. Some expose /tabbit; Pi documents /skill:tabbit; other clients may show skills under /skills or discover them automatically. Follow that client's own interface. A skill being visible only teaches the agent a workflow. It does not install the launcher, authenticate the site, or establish a connection.

In a local client, request a new task tab in the current Tabbit environment. Keep the site login in that browser profile. Do not paste passwords or export session cookies into a prompt. A user may continue working in other tabs while the task tab remains available for review. The task tab is a convenience, not an isolation boundary for sensitive site data.

Build a source-linked research brief

Suppose GPT-5.5 Pro should prepare an internal brief from a signed-in analytics portal and public product documentation. Give it a narrow, read-only request. Tell it which section to inspect, the allowed output fields, and when to stop. Have it include source links and mark anything it could not verify.

Use this prompt as a starting point. Replace the bracketed values with non-sensitive instructions, not credentials:

Use the local Tabbit browser through the installed Tabbit CLI.
Task name: Q4 source brief
Goal: read the [named report section] and compare it with [public documentation URL].
Access: use the already signed-in Tabbit profile. Do not ask me for passwords or cookies.
Scope: read pages only. Do not click submit, publish, invite, delete, export, or change settings.
Return:
1. A 5-row table with claim, source URL, observed date, and confidence.
2. Up to 5 short quotations, each under 20 words, with its source URL.
3. A 150-word draft named "Q4 source brief - review required".
4. A separate list of facts you could not verify.
Stop after opening the named draft in a task tab. Do not send or publish it.
If login is missing, stop and ask me to sign in in Tabbit Browser.

The output is a draft for review, not an evidence database. Open each cited page in the task tab, confirm the claim still appears there, and check the report date. A visible account page is not proof that every linked resource has the same permissions. If the site prompts for MFA or a new permission, stop and handle it yourself.

A practical Tabbit workflow for Pro

Tabbit Browser fits this case because the work depends on the local signed-in browser context. The agent can use Tabbit CLI to read pages in a task tab, while you keep using your other tabs. The environment's separate test of the CLI confirmed that a second task could access a page after sign-in in the same Tabbit environment. That test used a localhost fixture and temporary test cookie. It proves session reuse in that setup only. It does not test GPT-5.5 Pro, a particular client, a production site, or external model integration.

The review step matters. Read the page the brief cites, inspect any numbers and dates, then edit the named draft. Ask the agent to revise the prose in the same task tab if needed. Keep the final send, publish, or export action for a person. See the first browser-agent task checklist, connecting an agent to an existing browser, and CLI versus MCP for browser tasks.

This is a read-only research workflow. Do not use it to approve invoices, change account settings, or submit forms. If a remote agent cannot reach the local CLI, ask it to produce the prompt and source checklist; hand that to a local client or perform the steps yourself. A remote task does not inherit a laptop's browser session by default.

A browser-agent user on Reddit described the failure bluntly: “the session cookie expires and the whole thing's dead in the water.” That is a general session warning, not evidence about GPT-5.5 Pro or Tabbit. Read the original discussion.

For a related workflow, see the GPT-5.5 overview, the GPT-5.5 Instant browser guide, and the Tabbit CLI setup for Codex.

This article pairs with the record-comparison workflow.

Also see the Tabbit CLI complete guide for launcher setup. OpenAI lists computer use and Skills as unsupported for GPT-5.5 Pro hosted tools, so verify that your chosen client exposes a supported local function or MCP connection before treating this workflow as available.

Troubleshoot by layer

If the model cannot be selected, check the client's OpenAI provider support and project access. If /tabbit is missing, inspect the client's skill search path or documentation; that failure says nothing about whether the CLI itself is installed. If the CLI starts but sees the wrong browser, stop and select the intended instance before opening the protected site. If the site is logged out, sign in yourself in Tabbit and retry the read-only task. Never repair a connection by copying a session cookie into the model prompt.

Next step

Install Tabbit Browser, confirm your local client supports the Pro model and Tabbit skill, then run the read-only prompt against a low-risk page. Keep the generated brief open in its task tab until a person has checked every source.

Secholar.L

Growth & Content at Tabbit

Secholar.L writes hands-on guides about AI browsers and agent workflows, comparing tools with real research and citing verifiable sources.