feat: add custom provider support to GitHub Action

github/README.md

@@ -42,7 +42,7 @@ This will walk you through installing the GitHub app, creating the workflow, and
 
 ### Manual Setup
 
-1. Install the GitHub app https://github.com/apps/opencode-agent. Make sure it is installed on the target repository.
+1. Install the GitHub app <https://github.com/apps/opencode-agent>. Make sure it is installed on the target repository.
 2. Add the following workflow file to `.github/workflows/opencode.yml` in your repo. Set the appropriate `model` and required API keys in `env`.
 
    ```yml
@@ -76,9 +76,82 @@ This will walk you through installing the GitHub app, creating the workflow, and
 
 3. Store the API keys in secrets. In your organization or project **settings**, expand **Secrets and variables** on the left and select **Actions**. Add the required API keys.
 
+## Custom Provider Configuration
+
+You can configure custom providers using an `opencode.json` config file in your repository root:
+
+### Basic Usage with Config File
+
+1. Create `.github/opencode.json` in your repository:
+
+   ```json
+   {
+     "model": "custom-provider/my-model",
+     "provider": {
+       "custom-provider": {
+         "npm": "@ai-sdk/openai-compatible",
+         "models": {
+           "my-model": {
+             "name": "My Custom Model"
+           }
+         },
+         "options": {
+           "apiKey": "{env:CUSTOM_API_KEY}",
+           "baseURL": "{env:CUSTOM_BASE_URL}"
+         }
+       }
+     }
+   }
+   ```
+
+2. Update your workflow to use the config:
+
+   ```yml
+   - name: Run opencode
+     uses: sst/opencode/github@latest
+     env:
+       CUSTOM_API_KEY: ${{ secrets.CUSTOM_API_KEY }}
+       CUSTOM_BASE_URL: ${{ secrets.CUSTOM_BASE_URL }}
+     # No model parameter needed - will automatically use .github/opencode.json
+   ```
+
+### Advanced Configuration
+
+You can also specify a custom config file path and pass environment variables:
+
+```yml
+- name: Run opencode
+  uses: sst/opencode/github@latest
+  with:
+    config: opencode-ci.json
+    config_env: |
+      CUSTOM_API_KEY=${{ secrets.CUSTOM_API_KEY }}
+      CUSTOM_BASE_URL=https://api.example.com
+      DEBUG=true
+  # model parameter will override config if specified
+```
+
+### Action Inputs
+
+| Input        | Description                                                   | Required | Default                 |
+| ------------ | ------------------------------------------------------------- | -------- | ----------------------- |
+| `model`      | Model to use (overrides config file)                          | No       | -                       |
+| `config`     | Path to opencode config file                                  | No       | Auto-discovery          |
+| `config_env` | Environment variables for config (multiline key=value format) | No       | -                       |
+| `share`      | Share the opencode session                                    | No       | `true` for public repos |
+
+### Config File Discovery
+
+The action will automatically look for config files in this order:
+
+1. Path specified in `config` input
+2. `.github/opencode.json`
+3. `opencode.json` in repository root
+4. `.opencode/config.json` in repository root
+
 ## Support
 
-This is an early release. If you encounter issues or have feedback, please create an issue at https://github.com/sst/opencode/issues.
+This is an early release. If you encounter issues or have feedback, please create an issue at <https://github.com/sst/opencode/issues>.
 
 ## Development
 
@@ -122,7 +195,7 @@ Replace:
 - `"number":4` with the GitHub issue id
 - `"body":"hey opencode, summarize thread"` with comment body
 
-### Issue comment with image attachment.
+### Issue comment with image attachment
 
 ```
 --event '{"eventName":"issue_comment","repo":{"owner":"sst","repo":"hello-world"},"actor":"fwang","payload":{"issue":{"number":4},"comment":{"id":1,"body":"hey opencode, what is in my image ![Image](https://github.com/user-attachments/assets/xxxxxxxx)"}}}'

github/action.yml

@@ -6,8 +6,16 @@ branding:
 
 inputs:
   model:
-    description: "Model to use"
-    required: true
+    description: "Model to use (overrides config file)"
+    required: false
+
+  opencode_config:
+    description: "Path to opencode config file (defaults to .github/opencode.json)"
+    required: false
+
+  config_env:
+    description: "Environment variables for config (multiline key=value format)"
+    required: false
 
   share:
     description: "Share the opencode session (defaults to true for public repos)"
@@ -26,4 +34,6 @@ runs:
       run: opencode github run
       env:
         MODEL: ${{ inputs.model }}
+        OPENCODE_CONFIG: ${{ inputs.config }}
+        CONFIG_ENV: ${{ inputs.config_env }}
         SHARE: ${{ inputs.share }}

packages/opencode/src/cli/cmd/github.ts

@@ -19,6 +19,7 @@ import { Identifier } from "../../id/id"
 import { Provider } from "../../provider/provider"
 import { Bus } from "../../bus"
 import { MessageV2 } from "../../session/message-v2"
+import { Config } from "../../config/config"
 
 type GitHubAuthor = {
   login: string
@@ -129,7 +130,7 @@ export const GithubCommand = cmd({
   command: "github",
   describe: "manage GitHub agent",
   builder: (yargs) => yargs.command(GithubInstallCommand).command(GithubRunCommand).demandCommand(),
-  async handler() {},
+  async handler() { },
 })
 
 export const GithubInstallCommand = cmd({
@@ -364,7 +365,8 @@ export const GithubRunCommand = cmd({
         process.exit(1)
       }
 
-      const { providerID, modelID } = normalizeModel()
+      await loadConfiguration()
+      const { providerID, modelID } = await normalizeModel()
       const runId = normalizeRunId()
       const share = normalizeShare()
       const { owner, repo } = context.repo
@@ -481,9 +483,91 @@ export const GithubRunCommand = cmd({
       }
       process.exit(exitCode)
 
-      function normalizeModel() {
+      function parseConfigEnvironment(): Record<string, string> {
+        const configEnv = process.env["CONFIG_ENV"]
+        if (!configEnv) return {}
+
+        try {
+          // Parse key=value format only
+          const result: Record<string, string> = {}
+          configEnv.split("\n").forEach((line) => {
+            const trimmed = line.trim()
+            if (trimmed && !trimmed.startsWith("#")) {
+              const [key, ...valueParts] = trimmed.split("=")
+              if (key && valueParts.length > 0) {
+                result[key.trim()] = valueParts.join("=").trim()
+              }
+            }
+          })
+
+          return result
+        } catch (error) {
+          console.warn("Failed to parse CONFIG_ENV, ignoring:", error)
+          return {}
+        }
+      }
+
+      async function loadConfiguration() {
+        // Parse and set additional environment variables
+        const additionalEnv = parseConfigEnvironment()
+        for (const [key, value] of Object.entries(additionalEnv)) {
+          process.env[key] = value
+          console.log(`Set environment variable: ${key}`)
+        }
+
+        // Load config file if specified or discover default
+        const configPath = process.env["OPENCODE_CONFIG"]
+        if (configPath) {
+          console.log(`Using config from OPENCODE_CONFIG: ${configPath}`)
+          try {
+            // Check if config file exists
+            const fs = await import("fs")
+            const path = await import("path")
+            const fullPath = path.resolve(configPath)
+            if (!fs.existsSync(fullPath)) {
+              throw new Error(`Config file not found: ${fullPath}`)
+            }
+            console.log(`Config file found: ${fullPath}`)
+          } catch (error) {
+            console.warn(`Config file error: ${error instanceof Error ? error.message : String(error)}`)
+          }
+        } else {
+          // Auto-discover config files and set OPENCODE_CONFIG
+          const fs = await import("fs")
+          const path = await import("path")
+          const defaultConfigs = [".github/opencode.json", "opencode.json", ".opencode/config.json"]
+
+          for (const defaultConfig of defaultConfigs) {
+            if (fs.existsSync(defaultConfig)) {
+              const fullPath = path.resolve(defaultConfig)
+              console.log(`Found default config: ${defaultConfig}`)
+              console.log(`Setting OPENCODE_CONFIG to: ${fullPath}`)
+              process.env["OPENCODE_CONFIG"] = fullPath
+              break
+            }
+          }
+        }
+      }
+
+      async function normalizeModel() {
         const value = process.env["MODEL"]
-        if (!value) throw new Error(`Environment variable "MODEL" is not set`)
+
+        // If MODEL is not set, try to get default from config
+        if (!value) {
+          try {
+            const cfg = await Config.get()
+            if (cfg.model) {
+              console.log(`Using default model from config: ${cfg.model}`)
+              const { providerID, modelID } = Provider.parseModel(cfg.model)
+              if (!providerID.length || !modelID.length)
+                throw new Error(`Invalid model ${cfg.model}. Model must be in the format "provider/model".`)
+              return { providerID, modelID }
+            }
+          } catch (error) {
+            console.warn(`Failed to load config: ${error instanceof Error ? error.message : String(error)}`)
+          }
+          throw new Error(`Environment variable "MODEL" is not set and no default model found in config`)
+        }
 
         const { providerID, modelID } = Provider.parseModel(value)
 
@@ -694,18 +778,18 @@ export const GithubRunCommand = cmd({
       async function exchangeForAppToken(token: string) {
         const response = token.startsWith("github_pat_")
           ? await fetch("https://api.opencode.ai/exchange_github_app_token_with_pat", {
-              method: "POST",
-              headers: {
-                Authorization: `Bearer ${token}`,
-              },
-              body: JSON.stringify({ owner, repo }),
-            })
+            method: "POST",
+            headers: {
+              Authorization: `Bearer ${token}`,
+            },
+            body: JSON.stringify({ owner, repo }),
+          })
           : await fetch("https://api.opencode.ai/exchange_github_app_token", {
-              method: "POST",
-              headers: {
-                Authorization: `Bearer ${token}`,
-              },
-            })
+            method: "POST",
+            headers: {
+              Authorization: `Bearer ${token}`,
+            },
+          })
 
         if (!response.ok) {
           const responseJson = (await response.json()) as { error?: string }