feat: add default fast models for explore agents

packages/opencode/src/provider/provider.ts

@@ -1231,6 +1231,42 @@ export namespace Provider {
     }
   }
 
+  async function pick(providerID: string, query: string[]) {
+    const provider = await state().then((state) => state.providers[providerID])
+    if (!provider) return
+
+    const models = Object.keys(provider.models)
+    for (const item of query) {
+      if (providerID === "amazon-bedrock") {
+        const prefixes = ["global.", "us.", "eu."]
+        const candidates = models.filter((model) => model.toLowerCase().includes(item.toLowerCase()))
+
+        // Model selection priority:
+        // 1. global. prefix (works everywhere)
+        // 2. User's region prefix (us., eu.)
+        // 3. Unprefixed model
+        const best = candidates.find((model) => model.startsWith("global."))
+        if (best) return getModel(providerID, best)
+
+        const region = provider.options?.region
+        if (region) {
+          const prefix = region.split("-")[0]
+          if (prefix === "us" || prefix === "eu") {
+            const hit = candidates.find((model) => model.startsWith(`${prefix}.`))
+            if (hit) return getModel(providerID, hit)
+          }
+        }
+
+        const bare = candidates.find((model) => !prefixes.some((prefix) => model.startsWith(prefix)))
+        if (bare) return getModel(providerID, bare)
+        continue
+      }
+
+      const hit = models.find((model) => model.toLowerCase().includes(item.toLowerCase()))
+      if (hit) return getModel(providerID, hit)
+    }
+  }
+
   export async function getSmallModel(providerID: string) {
     const cfg = await Config.get()
 
@@ -1239,55 +1275,26 @@ export namespace Provider {
       return getModel(parsed.providerID, parsed.modelID)
     }
 
-    const provider = await state().then((state) => state.providers[providerID])
-    if (provider) {
-      let priority = [
-        "claude-haiku-4-5",
-        "claude-haiku-4.5",
-        "3-5-haiku",
-        "3.5-haiku",
-        "gemini-3-flash",
-        "gemini-2.5-flash",
-        "gpt-5-nano",
-      ]
-      if (providerID.startsWith("opencode")) {
-        priority = ["gpt-5-nano"]
-      }
-      if (providerID.startsWith("github-copilot")) {
-        // prioritize free models for github copilot
-        priority = ["gpt-5-mini", "claude-haiku-4.5", ...priority]
-      }
-      for (const item of priority) {
-        if (providerID === "amazon-bedrock") {
-          const crossRegionPrefixes = ["global.", "us.", "eu."]
-          const candidates = Object.keys(provider.models).filter((m) => m.includes(item))
-
-          // Model selection priority:
-          // 1. global. prefix (works everywhere)
-          // 2. User's region prefix (us., eu.)
-          // 3. Unprefixed model
-          const globalMatch = candidates.find((m) => m.startsWith("global."))
-          if (globalMatch) return getModel(providerID, globalMatch)
-
-          const region = provider.options?.region
-          if (region) {
-            const regionPrefix = region.split("-")[0]
-            if (regionPrefix === "us" || regionPrefix === "eu") {
-              const regionalMatch = candidates.find((m) => m.startsWith(`${regionPrefix}.`))
-              if (regionalMatch) return getModel(providerID, regionalMatch)
-            }
-          }
-
-          const unprefixed = candidates.find((m) => !crossRegionPrefixes.some((p) => m.startsWith(p)))
-          if (unprefixed) return getModel(providerID, unprefixed)
-        } else {
-          for (const model of Object.keys(provider.models)) {
-            if (model.includes(item)) return getModel(providerID, model)
-          }
-        }
-      }
+    let query = [
+      "claude-haiku-4-5",
+      "claude-haiku-4.5",
+      "3-5-haiku",
+      "3.5-haiku",
+      "gemini-3-flash",
+      "gemini-2.5-flash",
+      "gpt-5-nano",
+    ]
+    if (providerID.startsWith("opencode")) {
+      query = ["gpt-5-nano"]
+    }
+    if (providerID.startsWith("github-copilot")) {
+      // prioritize free models for github copilot
+      query = ["gpt-5-mini", "claude-haiku-4.5", ...query]
     }
 
+    const model = await pick(providerID, query)
+    if (model) return model
+
     // Check if opencode provider is available before using it
     const opencodeProvider = await state().then((state) => state.providers["opencode"])
     if (opencodeProvider && opencodeProvider.models["gpt-5-nano"]) {
@@ -1297,6 +1304,22 @@ export namespace Provider {
     return undefined
   }
 
+  export async function getExploreModel(providerID: string) {
+    const model = await pick(providerID, [
+      "gpt-5.3-codex-spark",
+      "claude-haiku-4-5",
+      "claude-haiku-4.5",
+      "gemini-3-flash",
+      "minimax-m2.5",
+      "minimax-m2-5",
+      "glm-5",
+      "kimi-k2.5",
+      "kimi-k2-5",
+    ])
+    if (model) return model
+    return undefined
+  }
+
   const priority = ["gpt-5", "claude-sonnet-4", "big-pickle", "gemini-3-pro"]
   export function sort(models: Model[]) {
     return sortBy(

packages/opencode/src/tool/task.ts

@@ -5,6 +5,7 @@ import { Session } from "../session"
 import { MessageV2 } from "../session/message-v2"
 import { Identifier } from "../id/id"
 import { Agent } from "../agent/agent"
+import { Provider } from "../provider/provider"
 import { SessionPrompt } from "../session/prompt"
 import { iife } from "@/util/iife"
 import { defer } from "@/util/defer"
@@ -102,11 +103,30 @@ export const TaskTool = Tool.define("task", async (ctx) => {
       })
       const msg = await MessageV2.get({ sessionID: ctx.sessionID, messageID: ctx.messageID })
       if (msg.info.role !== "assistant") throw new Error("Not an assistant message")
+      const info = msg.info
+
+      const model = await iife(async () => {
+        if (agent.model) return agent.model
+        if (agent.name !== "explore") {
+          return {
+            modelID: info.modelID,
+            providerID: info.providerID,
+          }
+        }
 
-      const model = agent.model ?? {
-        modelID: msg.info.modelID,
-        providerID: msg.info.providerID,
-      }
+        const pick = await Provider.getExploreModel(info.providerID)
+        if (pick) {
+          return {
+            modelID: pick.id,
+            providerID: pick.providerID,
+          }
+        }
+
+        return {
+          modelID: info.modelID,
+          providerID: info.providerID,
+        }
+      })
 
       ctx.metadata({
         title: params.description,

packages/opencode/test/provider/provider.test.ts

@@ -964,6 +964,129 @@ test("getSmallModel respects config small_model override", async () => {
   })
 })
 
+test("getExploreModel matches fallback models case-insensitively", async () => {
+  await using tmp = await tmpdir({
+    config: {
+      provider: {
+        "custom-provider": {
+          name: "Custom Provider",
+          npm: "@ai-sdk/openai-compatible",
+          api: "https://api.custom.com/v1",
+          env: ["CUSTOM_API_KEY"],
+          models: {
+            "MiniMax-M2-5": {
+              name: "MiniMax M2.5",
+              tool_call: true,
+              limit: {
+                context: 128000,
+                output: 4096,
+              },
+            },
+            "GLM-5": {
+              name: "GLM-5",
+              tool_call: true,
+              limit: {
+                context: 128000,
+                output: 4096,
+              },
+            },
+            "Kimi-K2-5": {
+              name: "Kimi K2.5",
+              tool_call: true,
+              limit: {
+                context: 128000,
+                output: 4096,
+              },
+            },
+          },
+          options: {
+            apiKey: "custom-key",
+          },
+        },
+      },
+    },
+  })
+  await Instance.provide({
+    directory: tmp.path,
+    fn: async () => {
+      const model = await Provider.getExploreModel("custom-provider")
+      expect(model).toBeDefined()
+      expect(model?.id).toBe("MiniMax-M2-5")
+    },
+  })
+})
+
+test("getExploreModel matches kimi separator variant", async () => {
+  await using tmp = await tmpdir({
+    config: {
+      provider: {
+        "custom-provider": {
+          name: "Custom Provider",
+          npm: "@ai-sdk/openai-compatible",
+          api: "https://api.custom.com/v1",
+          env: ["CUSTOM_API_KEY"],
+          models: {
+            "Kimi-K2-5": {
+              name: "Kimi K2.5",
+              tool_call: true,
+              limit: {
+                context: 128000,
+                output: 4096,
+              },
+            },
+          },
+          options: {
+            apiKey: "custom-key",
+          },
+        },
+      },
+    },
+  })
+  await Instance.provide({
+    directory: tmp.path,
+    fn: async () => {
+      const model = await Provider.getExploreModel("custom-provider")
+      expect(model).toBeDefined()
+      expect(model?.id).toBe("Kimi-K2-5")
+    },
+  })
+})
+
+test("getExploreModel returns undefined when no explore model matches", async () => {
+  await using tmp = await tmpdir({
+    config: {
+      provider: {
+        "custom-provider": {
+          name: "Custom Provider",
+          npm: "@ai-sdk/openai-compatible",
+          api: "https://api.custom.com/v1",
+          env: ["CUSTOM_API_KEY"],
+          models: {
+            "custom-model": {
+              name: "Custom Model",
+              tool_call: true,
+              limit: {
+                context: 128000,
+                output: 4096,
+              },
+            },
+          },
+          options: {
+            apiKey: "custom-key",
+          },
+        },
+      },
+    },
+  })
+  await Instance.provide({
+    directory: tmp.path,
+    fn: async () => {
+      const model = await Provider.getExploreModel("custom-provider")
+      expect(model).toBeUndefined()
+    },
+  })
+})
+
 test("provider.sort prioritizes preferred models", () => {
   const models = [
     { id: "random-model", name: "Random" },