fix(core): discover local plugin packages

packages/app/src/context/server-session-v2-reducer.test.ts

@@ -69,6 +69,63 @@ describe("v2 session reducer", () => {
     })
   })
 
+  test("prefers durable selection predecessors and derives them for older events", () => {
+    const source: SessionMessageInfo[] = [
+      { id: "msg_previous_agent", type: "agent-switched", agent: "build", time: { created: 1 } },
+      {
+        id: "msg_previous_model",
+        type: "model-switched",
+        model: { id: "old", providerID: "provider" },
+        time: { created: 1 },
+      },
+    ]
+    const reducer = createV2SessionReducer()
+
+    const agent = reducer.reduce(
+      source,
+      event({
+        ...base,
+        id: "evt_agent",
+        type: "session.agent.selected",
+        data: { sessionID: "ses_1", agent: "plan", previous: "review" },
+      }),
+    )
+    const model = reducer.reduce(
+      source,
+      event({
+        ...base,
+        id: "evt_model",
+        type: "session.model.selected",
+        data: {
+          sessionID: "ses_1",
+          model: { id: "new", providerID: "provider" },
+          previous: { id: "durable", providerID: "provider" },
+        },
+      }),
+    )
+    const legacyAgent = reducer.reduce(
+      source,
+      event({
+        ...base,
+        id: "evt_legacy_agent",
+        type: "session.agent.selected",
+        data: { sessionID: "ses_1", agent: "plan" },
+      }),
+    )
+
+    expect(agent?.messages.at(-1)).toMatchObject({ type: "agent-switched", agent: "plan", previous: "review" })
+    expect(model?.messages.at(-1)).toMatchObject({
+      type: "model-switched",
+      model: { id: "new" },
+      previous: { id: "durable" },
+    })
+    expect(legacyAgent?.messages.at(-1)).toMatchObject({
+      type: "agent-switched",
+      agent: "plan",
+      previous: "build",
+    })
+  })
+
   test("folds tool, retry, and completion events", () => {
     const reducer = createV2SessionReducer()
     let messages: SessionMessageInfo[] = []

packages/app/src/context/server-session-v2-reducer.ts

@@ -61,6 +61,12 @@ export function createV2SessionReducer() {
           type: "agent-switched",
           metadata: event.metadata,
           agent: event.data.agent,
+          previous:
+            event.data.previous ??
+            source.findLast(
+              (item): item is Extract<SessionMessageInfo, { type: "agent-switched" | "assistant" }> =>
+                item.type === "agent-switched" || item.type === "assistant",
+            )?.agent,
           time: { created: event.created },
         })
       case "session.model.selected":
@@ -69,10 +75,12 @@ export function createV2SessionReducer() {
           type: "model-switched",
           metadata: event.metadata,
           model: event.data.model,
-          previous: source.findLast(
-            (item): item is Extract<SessionMessageInfo, { type: "model-switched" | "assistant" }> =>
-              item.type === "model-switched" || item.type === "assistant",
-          )?.model,
+          previous:
+            event.data.previous ??
+            source.findLast(
+              (item): item is Extract<SessionMessageInfo, { type: "model-switched" | "assistant" }> =>
+                item.type === "model-switched" || item.type === "assistant",
+            )?.model,
           time: { created: event.created },
         })
       case "session.synthetic":

packages/client/src/effect/api/api.ts

@@ -339,7 +339,11 @@ export type Endpoint5_31Output =
           readonly type: "session.agent.selected"
           readonly durable: { readonly aggregateID: string; readonly seq: Event.Seq; readonly version: Event.Version }
           readonly location?: Location.Ref | undefined
-          readonly data: { readonly sessionID: Session.ID; readonly agent: Agent.ID }
+          readonly data: {
+            readonly sessionID: Session.ID
+            readonly agent: Agent.ID
+            readonly previous?: Agent.ID | undefined
+          }
         }
       | {
           readonly id: Event.ID
@@ -348,7 +352,11 @@ export type Endpoint5_31Output =
           readonly type: "session.model.selected"
           readonly durable: { readonly aggregateID: string; readonly seq: Event.Seq; readonly version: Event.Version }
           readonly location?: Location.Ref | undefined
-          readonly data: { readonly sessionID: Session.ID; readonly model: Model.Ref }
+          readonly data: {
+            readonly sessionID: Session.ID
+            readonly model: Model.Ref
+            readonly previous?: Model.Ref | undefined
+          }
         }
       | {
           readonly id: Event.ID

packages/client/src/promise/generated/types.ts

@@ -436,7 +436,7 @@ export type SessionAgentSelected = {
   type: "session.agent.selected"
   durable: { aggregateID: string; seq: number; version: 1 }
   location?: LocationRef
-  data: { sessionID: string; agent: string }
+  data: { sessionID: string; agent: string; previous?: string }
 }
 
 export type SessionModelSelected = {
@@ -446,7 +446,7 @@ export type SessionModelSelected = {
   type: "session.model.selected"
   durable: { aggregateID: string; seq: number; version: 1 }
   location?: LocationRef
-  data: { sessionID: string; model: ModelRef }
+  data: { sessionID: string; model: ModelRef; previous?: ModelRef }
 }
 
 export type SessionMoved = {

packages/core/src/config/plugin/source.ts

@@ -4,7 +4,7 @@ import { Directory, Document, type Entry } from "@opencode-ai/schema/config"
 import { ConfigPlugin } from "@opencode-ai/schema/config/plugin"
 import { FSUtil } from "@opencode-ai/util/fs-util"
 import { makeLocationNode } from "@opencode-ai/util/effect/app-node"
-import { Context, Effect, Layer, Option, PubSub, Scope, Stream } from "effect"
+import { Context, Effect, Layer, Option, PubSub, Schema, Scope, Stream } from "effect"
 import path from "path"
 import { fileURLToPath } from "url"
 import { Config } from "../../config"
@@ -154,6 +154,12 @@ const scan = Effect.fn("ConfigPluginSource.scan")(function* (
 })
 
 const sourceDirectories = ["plugin", "plugins"] as const
+const Package = Schema.Struct({
+  exports: Schema.optional(Schema.Unknown),
+  module: Schema.optional(Schema.Unknown),
+  main: Schema.optional(Schema.Unknown),
+})
+const decodePackage = Schema.decodeUnknownOption(Package)
 
 function discoverDirectory(fs: FSUtil.Interface, directory: string) {
   return Effect.gen(function* () {
@@ -166,7 +172,38 @@ function discoverDirectory(fs: FSUtil.Interface, directory: string) {
         symlink: true,
       })
       .pipe(Effect.orElseSucceed(() => []))
-    return files.sort().map((target): Operation => ({ type: "add", target, options: {} }))
+    const children = yield* fs
+      .scan(`{${sourceDirectories.join(",")}}/*`, {
+        cwd: directory,
+        absolute: true,
+        include: "all",
+        dot: true,
+        symlink: true,
+      })
+      .pipe(Effect.orElseSucceed(() => []))
+    const directories = yield* Effect.filter(children.sort(), fs.isDir)
+    const packages = yield* Effect.forEach(directories, (child) => discoverPackage(fs, child))
+    return [...files.sort(), ...packages.filter((target): target is string => typeof target === "string")].map(
+      (target): Operation => ({ type: "add", target, options: {} }),
+    )
+  })
+}
+
+function discoverPackage(fs: FSUtil.Interface, directory: string) {
+  return Effect.gen(function* () {
+    const manifest = yield* fs
+      .readJson(path.join(directory, "package.json"))
+      .pipe(Effect.map(decodePackage), Effect.orElseSucceed(Option.none))
+    const configured = Option.isSome(manifest)
+      ? [manifest.value.exports, manifest.value.module, manifest.value.main].filter(
+          (entry): entry is string => typeof entry === "string",
+        )
+      : []
+    const target = yield* Effect.findFirst(
+      [...configured, "index.ts", "index.js"].map((entry) => path.resolve(directory, entry)),
+      fs.isFile,
+    )
+    return Option.getOrUndefined(target)
   })
 }
 

packages/core/src/session.ts

@@ -716,10 +716,11 @@ const layer = Layer.effect(
             .pipe(Effect.ignore, Effect.forkIn(scope, { startImmediately: true }), Effect.asVoid)
       }),
       switchAgent: Effect.fn("Session.switchAgent")(function* (input) {
-        yield* result.get(input.sessionID)
+        const session = yield* result.get(input.sessionID)
         yield* bus.publish(SessionEvent.AgentSelected, {
           sessionID: input.sessionID,
           agent: input.agent,
+          previous: session.agent,
         })
       }),
       switchModel: Effect.fn("Session.switchModel")(function* (input) {
@@ -733,6 +734,7 @@ const layer = Layer.effect(
         yield* bus.publish(SessionEvent.ModelSelected, {
           sessionID: input.sessionID,
           model: input.model,
+          previous: session.model,
         })
       }),
       rename: Effect.fn("Session.rename")(function* (input) {

packages/core/src/session/message-updater.ts

@@ -61,7 +61,7 @@ export function update(adapter: Adapter, event: SessionEvent.DurableEvent) {
       "session.usage.recorded": () => Effect.void,
       "session.agent.selected": (event) => {
         return Effect.gen(function* () {
-          const previous = yield* adapter.getAgent()
+          const previous = event.data.previous ?? (yield* adapter.getAgent())
           yield* adapter.appendMessage(
             SessionMessage.AgentSelected.make({
               id: SessionMessage.ID.fromEvent(event.id),
@@ -76,7 +76,7 @@ export function update(adapter: Adapter, event: SessionEvent.DurableEvent) {
       },
       "session.model.selected": (event) => {
         return Effect.gen(function* () {
-          const previous = yield* adapter.getModel()
+          const previous = event.data.previous ?? (yield* adapter.getModel())
           yield* adapter.appendMessage(
             SessionMessage.ModelSelected.make({
               id: SessionMessage.ID.fromEvent(event.id),

packages/core/test/config/plugin.test.ts

@@ -168,6 +168,69 @@ describe("PluginSupervisor config", () => {
     ),
   )
 
+  it.live("loads auto-discovered plugin packages from package metadata", () =>
+    withLocation(
+      undefined,
+      Effect.gen(function* () {
+        yield* ready()
+        const plugins = yield* Plugin.Service
+        expect((yield* plugins.list()).map((plugin) => String(plugin.id))).toContain("package-metadata")
+      }),
+      false,
+      async (directory) => {
+        const plugin = path.join(directory, ".opencode", "plugins", "package-metadata")
+        await fs.mkdir(plugin, { recursive: true })
+        await fs.writeFile(path.join(plugin, "package.json"), JSON.stringify({ exports: "./entry.ts" }))
+        await fs.writeFile(path.join(plugin, "entry.ts"), discoveredPlugin("package-metadata"))
+      },
+    ),
+  )
+
+  it.live("loads auto-discovered plugin packages from index fallback", () =>
+    withLocation(
+      undefined,
+      Effect.gen(function* () {
+        yield* ready()
+        const plugins = yield* Plugin.Service
+        expect((yield* plugins.list()).map((plugin) => String(plugin.id))).toContain("index-fallback")
+      }),
+      false,
+      async (directory) => {
+        const plugin = path.join(directory, ".opencode", "plugins", "index-fallback")
+        await fs.mkdir(plugin, { recursive: true })
+        await fs.writeFile(path.join(plugin, "index.js"), discoveredPlugin("index-fallback"))
+      },
+    ),
+  )
+
+  it.live("prefers package metadata over index fallback", () =>
+    withLocation(
+      undefined,
+      Effect.gen(function* () {
+        yield* ready()
+        const plugins = yield* Plugin.Service
+        const ids = (yield* plugins.list()).map((plugin) => String(plugin.id))
+        expect(ids).toContain("metadata-precedence")
+        expect(ids).not.toContain("module-collision")
+        expect(ids).not.toContain("main-collision")
+        expect(ids).not.toContain("index-collision")
+      }),
+      false,
+      async (directory) => {
+        const plugin = path.join(directory, ".opencode", "plugins", "collision")
+        await fs.mkdir(plugin, { recursive: true })
+        await fs.writeFile(
+          path.join(plugin, "package.json"),
+          JSON.stringify({ exports: "./entry.js", module: "./module.js", main: "./main.js" }),
+        )
+        await fs.writeFile(path.join(plugin, "entry.js"), discoveredPlugin("metadata-precedence"))
+        await fs.writeFile(path.join(plugin, "module.js"), discoveredPlugin("module-collision"))
+        await fs.writeFile(path.join(plugin, "main.js"), discoveredPlugin("main-collision"))
+        await fs.writeFile(path.join(plugin, "index.js"), discoveredPlugin("index-collision"))
+      },
+    ),
+  )
+
   staticIt.live("uses only internal and SDK plugins when the static source is wired", () =>
     Effect.gen(function* () {
       const sdk = yield* SdkPlugins.Service
@@ -389,3 +452,7 @@ export default Plugin.define({
 })
 `
 }
+
+function discoveredPlugin(id: string) {
+  return `export default { id: ${JSON.stringify(id)}, setup() {} }`
+}

packages/core/test/session-create.test.ts

@@ -654,7 +654,7 @@ describe("Session.create", () => {
       expect(yield* session.get(created.id)).toMatchObject({ agent: "plan" })
       expect(
         Array.from(yield* logEvents(session, created.id, true).pipe(Stream.drop(1), Stream.take(1), Stream.runCollect)),
-      ).toMatchObject([{ type: "session.agent.selected", data: { agent: "plan" } }])
+      ).toMatchObject([{ type: "session.agent.selected", data: { agent: "plan", previous: "build" } }])
       expect(yield* session.messages({ sessionID: created.id, order: "asc" })).toMatchObject([
         { type: "agent-switched", agent: "plan", previous: "build" },
       ])
@@ -678,7 +678,12 @@ describe("Session.create", () => {
   it.effect("switches the selected model through the durable Session event", () =>
     Effect.gen(function* () {
       const session = yield* Session.Service
-      const created = yield* session.create({ location })
+      const previous = Model.Ref.make({
+        id: Model.ID.make("haiku"),
+        providerID: Provider.ID.anthropic,
+        variant: Model.VariantID.make("default"),
+      })
+      const created = yield* session.create({ location, model: previous })
       const model = Model.Ref.make({
         id: Model.ID.make("sonnet"),
         providerID: Provider.ID.anthropic,
@@ -692,7 +697,10 @@ describe("Session.create", () => {
         yield* logEvents(session, created.id, true).pipe(Stream.drop(1), Stream.take(1), Stream.runCollect),
       )
       expect(bus).toMatchObject([{ type: "session.model.selected" }])
-      expect(bus[0]?.data).toEqual({ sessionID: created.id, model })
+      expect(bus[0]?.data).toEqual({ sessionID: created.id, model, previous })
+      expect(yield* session.messages({ sessionID: created.id, order: "asc" })).toMatchObject([
+        { type: "model-switched", model, previous },
+      ])
     }),
   )
 

packages/protocol/openapi.json

@@ -14373,6 +14373,9 @@
               },
               "agent": {
                 "type": "string"
+              },
+              "previous": {
+                "type": "string"
               }
             },
             "required": ["sessionID", "agent"],
@@ -14441,6 +14444,9 @@
               },
               "model": {
                 "$ref": "#/components/schemas/Model.Ref"
+              },
+              "previous": {
+                "$ref": "#/components/schemas/Model.Ref"
               }
             },
             "required": ["sessionID", "model"],

packages/schema/src/session-event.ts

@@ -69,6 +69,7 @@ export const AgentSelected = Event.durable({
   schema: {
     ...Base,
     agent: Agent.ID,
+    previous: Agent.ID.pipe(optional),
   },
 })
 export type AgentSelected = typeof AgentSelected.Type
@@ -79,6 +80,7 @@ export const ModelSelected = Event.durable({
   schema: {
     ...Base,
     model: Model.Ref,
+    previous: Model.Ref.pipe(optional),
   },
 })
 export type ModelSelected = typeof ModelSelected.Type

packages/www/openapi.json

@@ -14373,6 +14373,9 @@
               },
               "agent": {
                 "type": "string"
+              },
+              "previous": {
+                "type": "string"
               }
             },
             "required": ["sessionID", "agent"],
@@ -14441,6 +14444,9 @@
               },
               "model": {
                 "$ref": "#/components/schemas/Model.Ref"
+              },
+              "previous": {
+                "$ref": "#/components/schemas/Model.Ref"
               }
             },
             "required": ["sessionID", "model"],

packages/www/public/openapi.json

@@ -14373,6 +14373,9 @@
               },
               "agent": {
                 "type": "string"
+              },
+              "previous": {
+                "type": "string"
               }
             },
             "required": ["sessionID", "agent"],
@@ -14441,6 +14444,9 @@
               },
               "model": {
                 "$ref": "#/components/schemas/Model.Ref"
+              },
+              "previous": {
+                "$ref": "#/components/schemas/Model.Ref"
               }
             },
             "required": ["sessionID", "model"],