feat(sdk): add HttpApi client codegen

CONTEXT.md

@@ -55,6 +55,21 @@ Provider-neutral sampling and output controls, partitioned from provider semanti
 **PTY Environment**:
 The host-supplied environment overlay applied by the server when creating a PTY, observed for the request Location and resolved PTY working directory.
 
+**OpenCode Client**:
+The generated Effect API shared by networked and in-process consumers, executed through an `HttpClient` against the same `HttpApi` router and handlers.
+_Avoid_: Remote client
+
+**SDK Contract IR**:
+The runtime-neutral compiled representation of the authoritative `HttpApi`, preserving encoded and decoded type projections plus transport metadata so independent SDK emitters can choose their public value model and runtime interpreter.
+
+**Embedded OpenCode**:
+A scoped in-process host that structurally extends the **OpenCode Client**, supplies an in-memory HTTP transport, and exposes additional same-process capabilities directly.
+_Avoid_: Local implementation
+
+**Page**:
+A bounded ordered result containing `items` and opaque `previous` and `next` cursor links for navigating the same query in either direction.
+_Avoid_: Response envelope
+
 ## Relationships
 
 - A **System Context** is an opaque carrier composed from zero or more **Context Sources**.
@@ -100,6 +115,47 @@ The host-supplied environment overlay applied by the server when creating a PTY,
 - **Model Request Options** remain provider-semantic through Catalog resolution. The Session runner maps them into the LLM package's provider-option namespace; the selected protocol adapter alone owns provider wire encoding.
 - **Generation Controls**, protocol-semantic **Model Request Options**, and compatibility request body fields are separate Catalog domains. A shared ingestion adapter partitions legacy and models.dev AI-SDK-shaped options before routing.
 - The **PTY Environment** is a server concern rather than a Core PTY concern. PTY creation merges caller values, then the host overlay, then Core-forced terminal invariants such as `TERM` and `OPENCODE_TERMINAL`.
+- Networked and **Embedded OpenCode** use the same **OpenCode Client** and preserve the full HTTP encoding, routing, middleware, and decoding boundary; only the `HttpClient` transport differs.
+- The Effect-native network constructor obtains `HttpClient.HttpClient` from its environment so callers own transport selection, recording, tracing, retries, and tests. Convenience runtimes may provide a fetch transport separately.
+- Creating **Embedded OpenCode** is scoped. Closing its owning Scope releases the in-process server resources, database resources, registrations, and fibers.
+- **Embedded OpenCode** exposes shared client capabilities and embedded-only capabilities on one object; consumers do not navigate through a nested `.client` property.
+- The **OpenCode Client** uses plural consumer-facing capability groups such as `sessions`; internal server identifiers such as `server.session` and `session.get` do not define its public names.
+- The public `HttpApi` is authoritative for shared **OpenCode Client** capabilities: the server hosts those exact endpoint declarations and code generation consumes them directly. Public endpoints are not duplicated or projected from a separately named internal contract.
+- SDK generation reflects the public `HttpApi` once into an **SDK Contract IR**. Promise and Effect emitters share endpoint structure and transport metadata without being required to expose identical public values: an emitter may select encoded wire types, decoded domain types, compile-time brands, runtime validation, and its own execution abstraction independently.
+- The first Effect emitter is the rich projection: it exposes decoded Effect-native values, preserves brands and schema transformations, performs runtime schema decoding, and delegates transport interpretation to `HttpApiClient`. Lighter wire-shaped Effect output remains possible through another emitter policy rather than constraining the shared IR.
+- Initially, the rich Effect emitter regenerates private executable schemas and `HttpApi` groups from the **SDK Contract IR**, reproducing semantics exactly or rejecting generation. Importing authoritative schemas from a future dependency-leaf public API package remains an alternative emitter strategy, not a prerequisite refactor.
+- The first Promise emitter targets the same clean domain-oriented method organization rather than Hey API source compatibility. It returns unwrapped values directly, rejects declared and infrastructure failures, and begins with minimal client-level transport configuration; result wrappers, interceptors, and legacy generated signatures are outside the initial surface.
+- The first Promise emitter parses response syntax and trusts its generated structural types; it does not perform runtime structural validation. Malformed payload syntax fails, while a syntactically valid shape mismatch is not detected at the SDK boundary. Standalone validator generation remains an optional future emitter policy.
+- Declared Promise-client failures retain their tagged structural wire values and have generated type guards. Consumers do not depend on generated `Error` subclass identity, preserving discrimination across package copies and realms while remaining structurally aligned with Effect domain errors.
+- Promise-client infrastructure failures use one generated `ClientError` class with a structured reason such as transport failure, unexpected status, unsupported content type, or malformed response. Promise methods reject with either a tagged declared domain failure or `ClientError`, matching the Effect client's conceptual domain/infrastructure error division.
+- Promise methods accept a separate optional per-call transport-options argument containing `AbortSignal` and header overrides. Cancellation and transport metadata do not enter the domain input object; broader interceptor and response-mode APIs remain deferred.
+- Promise streaming methods return a lazy `AsyncIterable` directly rather than a Promise-wrapped stream object. Iteration opens the connection, `AbortSignal` cancels it, and ending iteration closes the underlying request; the Effect emitter analogously returns `Stream` directly.
+- Promise SSE connection establishment, declared HTTP failures, and infrastructure failures occur during `AsyncIterable` iteration, beginning with its first `next()` call, rather than during synchronous method construction.
+- Neither generated streaming runtime automatically reconnects after disconnection. Promise `AsyncIterable` and Effect `Stream` fail explicitly; live consumers refresh and resubscribe, while durable sequence-based resume remains explicit composition above the generated client.
+- Promise client construction is synchronous and network-free. It requires `baseUrl`, defaults to `globalThis.fetch`, accepts client-level headers, and merges them with per-call header overrides.
+- Effect client construction accepts an explicit `baseUrl` and obtains `HttpClient.HttpClient` from the Effect environment. It does not install fetch or duplicate per-call transport policy; callers transform/provide the client for headers, tracing, retries, recording, and tests, while fiber interruption owns cancellation.
+- Promise and Effect emitters each own their generated public type modules. The **SDK Contract IR**, not a physically shared generated type package, is the common source; this permits zero-Effect wire types and rich decoded Effect types to evolve independently.
+- Promise and Effect client outputs ship from `@opencode-ai/client` behind isolated root, `/effect`, and `/effect/embedded` exports. The root export has no runtime path to Effect; `/effect` contains only the rich network client and may use Effect as an optional peer dependency; `/effect/embedded` owns the heavy private Core/server dependency closure for the scoped embedded host. The package remains private until the authoritative public `HttpApi` is composed and packaging of embedded dependencies is settled.
+- A capability intended for both networked and **Embedded OpenCode** belongs in the authoritative public `HttpApi`; embedded-only same-process capabilities extend **Embedded OpenCode** separately.
+- `sessions.events({ sessionID, after })` is a public durable Session event stream. It verifies the Session, replays durable events after the optional aggregate sequence, continues with newly committed durable events, excludes live-only fragments, and is transported as SSE in both networked and embedded modes.
+- `events.subscribe()` is a distinct public instance-wide live stream for Session and non-Session activity. It has no replay guarantee and includes connection, heartbeat, and instance-disposal lifecycle events; consumers recover from disconnection by refreshing authoritative state.
+- A Session ID is not an optional filter on `events.subscribe()`: instance-wide live events and durable Session events have different schemas, replay guarantees, cursors, lifecycle events, and failure behavior.
+- The initial common OpenCode Client does not expose server-global event aggregation. `events.subscribe()` is bounded to the connected OpenCode instance or workspace; any future cross-instance administrative stream requires a separately designed API.
+- `events.subscribe()` does not automatically reconnect after transport loss. The live-only stream fails with `ClientError`; consumers refresh authoritative state before explicitly opening a new subscription because events missed during disconnection cannot be replayed.
+- `sessions.events({ sessionID, after })` returns the generated HTTP client's cold durable event stream and does not build reconnection policy into the endpoint or client constructor. Transport loss fails the stream with `ClientError`. Callers may compose an explicit resuming stream above it by retaining the last observed durable sequence and opening a new subscription with `after`; any reusable resume helper remains a separate API design question.
+- `sessions.list(...)` returns a **Page** in both networked and **Embedded OpenCode**; embedded execution does not define a separate unbounded array-returning list operation.
+- Session list cursors are opaque branded values carrying continuation query and ordering state. Consumers pass them back unchanged and do not inspect storage anchors or encoded filter fields.
+- A Session list continuation accepts only its opaque cursor. Scope, filters, ordering, and page size are fixed by the initial query and carried by that cursor.
+- `sessions.messages(...)` returns a **Page** and uses the same cursor discipline as `sessions.list(...)`: the initial request supplies `sessionID`, ordering, and page size; continuation supplies `sessionID` plus only an opaque branded message cursor carrying ordering, page size, direction, and message anchor. Using a cursor with another Session is invalid.
+- `sessions.message({ sessionID, messageID })` is a required resource lookup. An unknown Session fails with `SessionNotFoundError`; a known Session with an absent or differently owned message fails with `SessionMessageNotFoundError` without disclosing cross-Session ownership. Absence is not represented as `undefined` across the public HTTP boundary.
+- `sessions.interrupt({ sessionID })` first verifies that the durable Session exists, failing with `SessionNotFoundError` otherwise. For a known Session, interruption is idempotent: idle, already-settled, or locally unowned execution is a no-op.
+- `sessions.context({ sessionID })` preserves the existing message-only operation. It returns projected conversational messages selected as Session context; it does not include or represent the complete provider request context, whose baseline system context and other contributions remain separate.
+- **Open question**: Should a future, separately named operation expose the complete provider request context, including baseline system context, selected source contributions, and context-epoch metadata?
+- `sessions.prompt(...)` exposes `resume?: boolean`. Omitting it preserves durable admission followed by an advisory execution wake; `resume: false` requests durable admit-only behavior.
+- The public operation remains `sessions.prompt(...)`; `SessionInput.admit` is the internal primitive, while the public `Admission` result and `resume` option express its durable admission semantics.
+- `sessions.create(...)` accepts an optional `location`. Omission resolves through the connected OpenCode instance's default or current location; an explicit value selects a known location. Networked and embedded transports use the same handler semantics.
+- `sessions.switchAgent({ sessionID, agent })` is part of the common client alongside `sessions.switchModel(...)`. It affects subsequent Session activity and fails with `SessionNotFoundError` for an unknown Session.
+- A future Layer constructor may provide **Embedded OpenCode** using the same scoped creation path; it does not define a second implementation.
 - A **PTY Environment** adapter observes plugins in the request Location while passing the resolved PTY working directory to the hook; standalone servers use an empty adapter.
 - A **Mid-Conversation System Message** lowers to the provider's native chronological instruction role when supported and to a wrapped chronological fallback otherwise.
 - When the effective aggregate instruction set changes, its **Mid-Conversation System Message** includes the complete current ordered set and supersedes the prior aggregate value; when no ambient instructions remain, the message states that previously loaded instructions no longer apply.

packages/client/README.md

@@ -0,0 +1,11 @@
+# @opencode-ai/client
+
+Private generation target for clients derived directly from OpenCode's authoritative Effect `HttpApi`.
+
+## Entrypoints
+
+- `@opencode-ai/client`: zero-Effect Promise client using `fetch`.
+- `@opencode-ai/client/effect`: rich Effect network client using an environment-provided `HttpClient`.
+- `@opencode-ai/client/effect/embedded`: scoped embedded OpenCode host backed by Core and the in-memory HTTP router.
+
+The entry modules are intentionally empty until the authoritative public `HttpApi` is composed. Do not generate clients from the current internal server API.

packages/client/package.json

@@ -0,0 +1,28 @@
+{
+  "$schema": "https://json.schemastore.org/package.json",
+  "name": "@opencode-ai/client",
+  "private": true,
+  "type": "module",
+  "license": "MIT",
+  "exports": {
+    ".": "./src/index.ts",
+    "./effect": "./src/effect.ts",
+    "./effect/embedded": "./src/effect-embedded.ts"
+  },
+  "scripts": {
+    "typecheck": "tsgo --noEmit"
+  },
+  "peerDependencies": {
+    "effect": "4.0.0-beta.83"
+  },
+  "peerDependenciesMeta": {
+    "effect": {
+      "optional": true
+    }
+  },
+  "devDependencies": {
+    "@tsconfig/bun": "catalog:",
+    "@types/bun": "catalog:",
+    "@typescript/native-preview": "catalog:"
+  }
+}

packages/client/src/effect-embedded.ts

@@ -0,0 +1,2 @@
+// Embedded Effect host target. Intentionally empty until the public HttpApi is available.
+export {}

packages/client/src/effect.ts

@@ -0,0 +1,2 @@
+// Generated Effect network client target. Intentionally empty until the public HttpApi is available.
+export {}

packages/client/src/index.ts

@@ -0,0 +1,2 @@
+// Generated Promise client target. Intentionally empty until the public HttpApi is available.
+export {}

packages/client/tsconfig.json

@@ -0,0 +1,7 @@
+{
+  "$schema": "https://json.schemastore.org/tsconfig",
+  "extends": "@tsconfig/bun/tsconfig.json",
+  "compilerOptions": {
+    "lib": ["ESNext", "DOM", "DOM.Iterable"]
+  }
+}