feat(opencode): Command Support on Config with {cmd:}

packages/opencode/src/config/paths.ts

@@ -6,6 +6,8 @@ import { NamedError } from "@opencode-ai/util/error"
 import { Filesystem } from "@/util/filesystem"
 import { Flag } from "@/flag/flag"
 import { Global } from "@/global"
+import { $ } from "bun"
+import { withTimeout } from "@/util/timeout"
 
 export namespace ConfigPaths {
   export async function projectFiles(name: string, directory: string, worktree: string) {
@@ -81,12 +83,53 @@ export namespace ConfigPaths {
     return typeof input === "string" ? path.dirname(input) : input.dir
   }
 
-  /** Apply {env:VAR} and {file:path} substitutions to config text. */
+  /** Apply {env:VAR}, {file:path}, and {cmd:command} substitutions to config text. */
   async function substitute(text: string, input: ParseSource, missing: "error" | "empty" = "error") {
     text = text.replace(/\{env:([^}]+)\}/g, (_, varName) => {
       return process.env[varName] || ""
     })
 
+    const cmdMatches = Array.from(text.matchAll(/\{cmd:[^}]+\}/g))
+    if (cmdMatches.length) {
+      const configSource = source(input)
+      let out = ""
+      let cursor = 0
+
+      for (const match of cmdMatches) {
+        const token = match[0]
+        const index = match.index!
+        out += text.slice(cursor, index)
+
+        const lineStart = text.lastIndexOf("\n", index - 1) + 1
+        const prefix = text.slice(lineStart, index).trimStart()
+        if (prefix.startsWith("//")) {
+          out += token
+          cursor = index + token.length
+          continue
+        }
+
+        const command = token.replace(/^\{cmd:/, "").replace(/\}$/, "")
+        const parts = command.trim().split(/\s+/)
+        const cmd = parts[0]
+        const args = parts.slice(1)
+        const cmdResult = await withTimeout($`${cmd} ${args}`.quiet().nothrow(), 5_000)
+
+        if (cmdResult.exitCode !== 0) {
+          throw new InvalidError({
+            path: configSource,
+            message: `bad command reference: "${token}" command failed with exit code ${cmdResult.exitCode}: ${cmdResult.stderr}`,
+          })
+        }
+
+        const cmdOutput = cmdResult.stdout.toString().trim()
+        out += JSON.stringify(cmdOutput).slice(1, -1)
+        cursor = index + token.length
+      }
+
+      out += text.slice(cursor)
+      text = out
+    }
+
     const fileMatches = Array.from(text.matchAll(/\{file:[^}]+\}/g))
     if (!fileMatches.length) return text
 

packages/opencode/test/config/config.test.ts

@@ -102,6 +102,37 @@ test("loads JSONC config file", async () => {
   })
 })
 
+test("substitutes {cmd:} tokens in config file", async () => {
+  await using tmp = await tmpdir({
+    init: async (dir) => {
+      await Filesystem.write(
+        path.join(dir, "opencode.json"),
+        JSON.stringify({
+          $schema: "https://opencode.ai/config.json",
+          mcp: {
+            test: {
+              type: "remote",
+              url: "https://example.com/mcp",
+              headers: {
+                Authorization: "Bearer {cmd:echo test_token}",
+              },
+            },
+          },
+        }),
+      )
+    },
+  })
+
+  await Instance.provide({
+    directory: tmp.path,
+    fn: async () => {
+      const config = await Config.get()
+      const mcpConfig = config.mcp?.test as { type: "remote"; headers?: Record<string, string> } | undefined
+      expect(mcpConfig?.headers?.Authorization).toBe("Bearer test_token")
+    },
+  })
+})
+
 test("merges multiple config files with correct precedence", async () => {
   await using tmp = await tmpdir({
     init: async (dir) => {
@@ -1883,4 +1914,39 @@ describe("OPENCODE_CONFIG_CONTENT token substitution", () => {
       }
     }
   })
+
+  test("substitutes {cmd:} tokens", async () => {
+    const originalEnv = process.env["OPENCODE_CONFIG_CONTENT"]
+
+    try {
+      process.env["OPENCODE_CONFIG_CONTENT"] = JSON.stringify({
+        $schema: "https://opencode.ai/config.json",
+        mcp: {
+          github: {
+            type: "remote",
+            url: "https://example.com/mcp",
+            headers: {
+              Authorization: "Bearer {cmd:echo test_token}",
+            },
+          },
+        },
+      })
+
+      await using tmp = await tmpdir()
+      await Instance.provide({
+        directory: tmp.path,
+        fn: async () => {
+          const config = await Config.get()
+          const mcpConfig = config.mcp?.github as { type: "remote"; headers?: Record<string, string> } | undefined
+          expect(mcpConfig?.headers?.Authorization).toBe("Bearer test_token")
+        },
+      })
+    } finally {
+      if (originalEnv !== undefined) {
+        process.env["OPENCODE_CONFIG_CONTENT"] = originalEnv
+      } else {
+        delete process.env["OPENCODE_CONFIG_CONTENT"]
+      }
+    }
+  })
 })

packages/web/src/content/docs/config.mdx

@@ -633,7 +633,7 @@ Experimental options are not stable. They may change or be removed without notic
 
 ## Variables
 
-You can use variable substitution in your config files to reference environment variables and file contents.
+You can use variable substitution in your config files to reference environment variables, file contents, and command output.
 
 ---
 
@@ -688,3 +688,30 @@ These are useful for:
 - Keeping sensitive data like API keys in separate files.
 - Including large instruction files without cluttering your config.
 - Sharing common configuration snippets across multiple config files.
+
+---
+
+### Commands
+
+Use `{cmd:command}` to substitute the output of a shell command:
+
+```json title="opencode.json"
+{
+  "$schema": "https://opencode.ai/config.json",
+  "provider": {
+    "github": {
+      "options": {
+        "token": "{cmd:gh auth token}"
+      }
+    }
+  }
+}
+```
+
+The command is executed at config load time and its stdout is embedded into the config. Commands are useful for:
+
+- Retrieving secrets from password managers (e.g., `op read`, `bw get password`)
+- Getting dynamic values from CLI tools (e.g., `gh auth token`, `aws configure get`)
+- Integrating with external credential providers
+
+The command must exit with code 0. If it fails, opencode will throw an error with the command's stderr.