[BUG] claude.ai Chat: fixed ~323k context baseline, invariant under all client-side removal (Code/Cowork unaffected on same account)

Chat surface: fixed ~323k context baseline, invariant under all client-side removal

Summary

A bare hi in a brand-new chat fails immediately:

This request exceeds Claude's context limit by about 322,965 tokens. Try turning off some tools or shortening your message.

The Chat surface is completely unusable on this account. Claude Code and Cowork on the same account work normally.

Environment

• Claude Desktop 1.22209.3 (macOS 15 / Darwin 25.5.0, Apple Silicon)
• Also reproduces on claude.ai web in a clean browser session — so this is not client-specific
• Plan: Max
• Account age: older than 2 months. Active use resumed ~2 months ago alongside the current

local install; usage volume has been light throughout, both before and after.

• Memory store: measured small in effect — disabling Memory accounted for only ~11k of the

~334k baseline

• No large Projects attached; failure occurs in a plain, non-Project chat

Reproduction

1. Open a brand-new chat (web or Desktop)
2. Type hi
3. Request fails before any response with the context-limit error above

Persists across: full app quit, browser hard reload, logout/login, reboot.

Key finding: the baseline is invariant under removal

This is the diagnostic signal. Every client-side lever was exercised, including removals far
larger than the reported overage, with almost no effect:

| Action | Content removed | Overage after | Delta |
|---|---|---|---|
| baseline | — | ~350,000 | — |
| Removed 3 plugins (product-management, marketing, productivity) — 38 connector registrations | 38 MCP server registrations | 339,689 | ~-10k |
| Uninstalled acedatacloud-ai-media, acedatacloud-ai-tools, huggingface-skills | 484,069 tokens of SKILL.md content (measured on disk) | 335,067 | ~-4.6k |
| Removed iwork connector | 113 tool schemas | 333,897 | ~-1.2k |
| Disabled Memory | memory store | 322,965 | ~-11k |
| Total | >484k tokens of removable content | | ~-27k |

Removing 484,000 tokens of skill content moved the baseline by 4,600 tokens.
Removing 113 MCP tool schemas moved it by 1,170 tokens — roughly 10 tokens per tool, where
real tool schemas run 300–800 tokens each.

Conclusion: none of the content the client can enumerate or control is what is filling the
context window. Approximately 320k is being injected server-side from a source not exposed
to the user.

Why this is not issue #62175

The error string matches #62175 ("Load tools when needed" not deferring connector schemas),
but the arithmetic rules it out: removing 113 tool schemas changed the total by ~1.2k. Connector
schemas are demonstrably not the payload here. Filing separately to avoid being triaged as a
duplicate.

Control: second account, identical configuration

A second user on the same app version, who received the same 2026-07-15
knowledge-work-plugins migration, and who also uses Cowork, has a fully functional Chat
surface. Their connector/plugin set is a strict subset of the affected account's, but given the
invariance data above, plugin/connector count does not appear to be the operative variable.

Surface split

| Surface | Status |
|---|---|
| Chat (web) | broken |
| Chat (Desktop) | broken |
| Cowork | working |
| Claude Code | working |

Whatever the payload is, it is specific to how Chat assembles its context, and Cowork/Code
do not load it.

Request

Identify what is populating ~320k of context on this account's Chat surface. It is not visible
to the user and is not removable through any client-side setting: plugins, skills, connectors,
tools, memory, styles, or projects.

Impact

Chat is 100% unusable on a paid Max plan. Every user-accessible mitigation has been exhausted.