On loopback a call needs no key and the body's Content-Type isn't checked, so any page the user visited could send a "simple" text/plain POST to 127.0.0.1:3425 and spend their subscriptions without reading the reply. corsGuard now refuses a request whose Origin is an http(s) origin that is not on Settings → Network and sharing → Web pages, not loopback (localhost, *.localhost, 127.0.0.0/8, [::1], any port) and not the request's own (host:port equal to Host). usemagpie.ai still reads /v1/magpie/omarchy. No Origin (agents), "null" and non-http schemes (app://, file://, tauri://, vscode-webview://, chrome-extension://) pass as before: those clients could only call before by not enforcing CORS, and no web page can send those origins. Such a page never read a reply before (no CORS headers), so nothing that worked is refused. Verified: TestForeignPagesRefused (text/plain POSTs from https://evil.example and other foreign origins on every route family: /v1/chat/completions, /v1/responses, /v1/messages, count_tokens, /v1/systemone, /v1beta, /v1/embeddings, /v1/rerank, images, videos, the Codex backend path, /mcp, /_magpie/claude-mcp, /v1/magpie/*, /v1/models, the GET /v1/responses upgrade, OPTIONS; loopback, *.localhost, listed with a key, same-origin on a LAN address through lanGuard, no Origin, null, app://, file://, tauri://, vscode-webview://, chrome-extension:// answered) fails without the change (120 routes answered, the fake vendor reached 139 times). go test -tags nogui ./... green; -race -count=10 on the CORS tests; darwin, linux nogui and windows builds. The built binary served from a sandbox HOME on 127.0.0.1:3591: curl from the foreign origins got 403 on every route with the vendor untouched; the allowed origins got 200.
Subsystem design references
These pages describe current responsibilities, runtime paths, state, and contracts. Start with the subsystem relevant to your task, then follow its source links to verify the implementation you change.
| Subsystem | Reference |
|---|---|
| Built-in subscriptions moving to plugins | Provider and plugin ownership |
| Plugins that run on the gateway's requests and replies | Gateway middleware |
| Claude subscription turns across Claude Code runs | Claude subscription bridge |
| How the gateway picks a provider, key or account, and falls back | Gateway routing and fallback |
| Connecting an agent's config to the gateway, drift, disconnect, WSL twins | Agent wiring |
| Providers, keys, subscription accounts, refresh and allowance | Providers and accounts |
| Instructions, MCP servers, skills and RTK written into agents | Library |
Tray, panel, window, magpie web and the page's JSON API |
GUI app shell |
A subsystem can span several packages or repositories. Its reference describes the behavior those parts provide together; it does not need to list every function.
Maintain a reference
Update the owning reference in the same PR when a change alters a documented responsibility, interface, state transition, runtime path, compatibility rule, or failure behavior. An internal refactor that preserves these contracts does not require a prose change.
Keep each fact in one reference and link to it from agent instructions or other pages. Link to source files and named symbols rather than copying implementation details that change frequently. Explain field meanings and constraints that signatures alone do not express.
For a new reference, include the responsibilities and boundaries, source of truth, main runtime paths, state transitions, important constraints, and existing verification commands. Include failure and compatibility behavior where relevant. Document current behavior separately from proposed changes; the proposal belongs in its issue or PR.
Describe a PR's semantic changes
For each affected subsystem, explain the observable change with its trigger and before/after behavior. Include changes to interfaces, state, compatibility, and failure behavior when relevant. Link the affected reference, implementation, and verification evidence. State when a refactor preserves the documented behavior.
For example, a change to plugin adoption should explain which migration state and account condition trigger it, which implementation handles requests before and after adoption, and which test exercises that transition.
This is an author-provided explanation that a reviewer verifies against the diff and surrounding code. It is not an automatically proven compatibility verdict.
Review a change
- Identify the affected subsystem and the actual runtime path, including plugin or built-in ownership.
- Compare the claimed before/after behavior with the base and head implementation. Trace relevant callers and state transitions beyond the changed lines.
- Check that changed contracts appear in the owning reference and that source links still resolve.
- Check that the cited tests or runtime evidence exercise the claimed behavior. Report checks that were not run.
A documentation update alone does not prove the implementation. Existing tests and runtime evidence remain necessary for behavior changes.