codex - 💡(How to fix) Fix New chat creation fails with AbsolutePathBuf deserialized without a base path — reproduces across all trusted workspaces (Windows VS Code extension 26.513.21555)

Environment

VS Code extension: openai.chatgpt version 26.513.21555 (openai.chatgpt-26.513.21555-win32-x64) OS: Windows 11 Auth: ChatGPT account (Business plan) Codex CLI: also installed via npm (@openai/codex), latest

Reproduction

Open VS Code in any trusted workspace listed in ~/.codex/config.toml Click the Codex panel Type any prompt (e.g., hello) and press Enter

Expected A new chat session opens and Codex responds. Actual Red error banner: Error starting chat — Invalid request: AbsolutePathBuf deserialized without a base path. The attempt appears in the task list with a warning icon but never opens. Observations

Continuing an existing task works correctly and returns valid GPT-5.5 responses — auth, network, model routing, plugins are all healthy. The bug is isolated to new-chat creation. Reproduces across multiple distinct workspaces (AI-Office-Manager, HR-Planning-Hub-Prod, more). Not project-specific. An empty no-workspace window gives a different and expected message: "Add a project to use Codex". So the bug triggers specifically when a trusted project context is loaded during new-chat init.

Already ruled out

No [agents.] blocks in ~/.codex/config.toml (so not #19257 / #19261) No ~/.codex/agents/ folder No project-level .codex/config.toml Not WSL agent mode (Windows native, sandbox = "unelevated") — so not #16815 Stripped \?\ Windows long-path prefixes from [marketplaces.] source lines → no effect, restored Full cache wipe of ~/.codex/.tmp and ~/.cache/codex-runtimes (Codex re-fetched cleanly) → no effect Uninstall + reinstall both Claude Code and Codex extensions → no effect Sign out + sign back in → no effect Model 5.5 High → 5.5 Medium → no effect Auto-review → Default permissions → no effect Only one VS Code window open → no effect

Hypothesis Looks like another AbsolutePathBuf deserialization site missing an AbsolutePathBufGuard, similar to #19257 / #19261 but on the new-chat session creation path rather than the agent role config path.