deepseek-harness/packages/client/connection

@deepseek-ai/dsh-client-connection

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Wire consumer layer: the client plugin's apply mounts ctx.connection (shared api client + current-page loopback state + single-consumer stream-loop starter); the export face carries the wire contract types, the AbstractApiClient seam, and the loop's sink/config types. The real browser carrier uses HTTP POST for unary and respond operations and opens one downlink-only WebSocket each for events.mux and events.host; the fixture and in-process carriers continue to satisfy the same two-stream abstraction. Loopback hostname classification stays package-internal: the /api Host fence and WebSocket upgrades use it directly, while other client plugins consume the derived ctx.connection.isLoopback state. The node half's /api route pins the privileged method set (host.pickDirectory, host.openPath, and the whole configuration plane — settings.describe, settings.openDocument, settings.update, settings.replace, settings.mutate, credentials.describe, credentials.set, and credentials.unset; reads and native actions included, since describing returns the exposed configuration, opening acts on the Host desktop, and probing an arbitrary reference reports where a credential comes from) to loopback by passing the trust fence with an empty trust list — a declared trustedHosts authority reaches every other method, while these stay loopback-local until a real authentication layer exists. The platform subclasses (WebApiClient/FixtureApiClient), the ConnectionController loop, and the fixture data source are package-internal — apply selects and drives them; tests reach them via src. The downlink boundary is documented in the WebSocket downlink carrier Agent Note; the protocol contract is api-contracts v3 §3.

/api browser-trust fence

The node half guards every entry under /api before bridging or upgrading (src/api-request-trust.ts). Every request — browser-marked or not — must present a Host that is a loopback authority or matches a trustedHosts entry: exact on host:port entries, any port on port-less entries, both sides compared through WHATWG normalization (DNS-rebinding defense). There is deliberately no shortcut for unmarked HTTP requests: over plain HTTP a browser attaches neither Origin nor Fetch-Metadata to image and navigation reads, so an unmarked request may still be a rebound browser read with a readable response, and Host is the one header rebinding cannot forge; a browser WebSocket handshake carries Origin and passes the same comparison. Non-browser clients pass the same fence via loopback, the CLI-derived LAN IP literals, or a declared authority. When markers are present, an attached Origin must equal the Host authority, and an explicit sec-fetch-site: cross-site marker is refused. A trustedHosts entry that is not a bare, canonical host[:port] authority — one WHATWG parsing reads back exactly as written — fails the plugin load loudly: parsing would otherwise quietly authorize the hostname inside harness.internal/path, or broaden a dangling-colon or zero-padded port to an any-port grant. HTTP failures answer plain 403 before any RPC dispatch; upgrade failures reject the handshake before any event stream starts. A non-loopback (--host 0.0.0.0) deployment therefore needs its serving authorities trusted: the dsh CLI derives the machine's LAN IP literals itself and its --trusted-host flag declares named ones, so trustedHosts in cordis.yml is for compositions the CLI does not boot. The fence is deliberately not an authentication layer — reachability policy stays with the webserver binding, and auth remains deferred work. Decision record: the api browser-trust boundary Agent Note.

/api WebSocket downlinks

/api/events.mux and /api/events.host each accept a WebSocket upgrade and send only the corresponding ServerRequest text messages to the browser; the client sends no application data over these sockets. If either socket ends, the current connection generation fails and rebuilds both streams; readiness still requires both sockets to be open and the host.describe HTTP call to succeed. Host teardown terminates both sockets, aborts their sources, and waits for source cleanup before returning. Ordinary network GETs to these paths return 426 with no SSE fallback; toFetchHandler's SSE codec serves only the isomorphic in-process carrier.

Keyless fixture

Any fixture query parameter selects the in-memory carrier. fixture=empty starts with no Workspace or Session; fixturePrompt=reject rejects prompts before acceptance; fixtureAttach=fail publishes a Session but rejects its Workspace attachment; fixtureSessionCreate=drop-response publishes and frames a Session before dropping the create response; and fixtureFrames=workspace-first reverses the default session-first create-frame order. Workspace creation by name/path and caller-preallocated SessionIds remain deterministic enough for assembled Web tests to reconcile list and frame arrival. Fixture content search preserves the production-facing unicode61-style case, diacritic, and token-phrase behavior and returns a match-centered snippet of at most 120 Unicode code points.

Model Experience

None, as the wire consumer layer moves already-composed messages between browser and host; nothing here reaches a model request.

KV Cache effect

None; this package neither assembles nor sends a provider request.

Known Limitations and Deferred Work

• history's implicit resume is arguable — opening history on an unattached session pulls an agent up host-side; the pure-persistence-read alternative is recorded in the rt-core reconciliation ledger, unchanged in P-I. This package's consumers see it as latency on first open.
• ToolEventView/ToolCallView/ToolResultView re-exports are scheduled for removal — they fall when the toolview migration deletes the host viewFor line (presentation belongs to the client); the fixture keeps a local viewFor mirror until then.