diff --git a/packages/function/src/api.ts b/packages/function/src/api.ts
index 58c74fe32254..9cb2897f99dc 100644
--- a/packages/function/src/api.ts
+++ b/packages/function/src/api.ts
@@ -5,6 +5,7 @@ import { jwtVerify, createRemoteJWKSet } from "jose"
 import { createAppAuth } from "@octokit/auth-app"
 import { Octokit } from "@octokit/rest"
 import { Resource } from "sst"
+import { parseGithubOidcSub } from "./github-oidc"
 
 type Env = {
   SYNC_SERVER: DurableObjectNamespace<SyncServer>
@@ -275,36 +276,43 @@ export default new Hono<{ Bindings: Env }>()
         issuer: GITHUB_ISSUER,
         audience: EXPECTED_AUDIENCE,
       })
-      const sub = payload.sub // e.g. 'repo:my-org/my-repo:ref:refs/heads/main'
-      const parts = sub.split(":")[1].split("/")
-      owner = parts[0]
-      repo = parts[1]
+      // classic: repo:owner/name:ref:...
+      // immutable: repo:owner@id/name@id:ref:...
+      const parsed = parseGithubOidcSub(payload.sub ?? "")
+      owner = parsed.owner
+      repo = parsed.repo
     } catch (err) {
       console.error("Token verification failed:", err)
       return c.json({ error: "Invalid or expired token" }, { status: 403 })
     }
 
-    // Create app JWT token
-    const auth = createAppAuth({
-      appId: Resource.GITHUB_APP_ID.value,
-      privateKey: Resource.GITHUB_APP_PRIVATE_KEY.value,
-    })
-    const appAuth = await auth({ type: "app" })
+    try {
+      // Create app JWT token
+      const auth = createAppAuth({
+        appId: Resource.GITHUB_APP_ID.value,
+        privateKey: Resource.GITHUB_APP_PRIVATE_KEY.value,
+      })
+      const appAuth = await auth({ type: "app" })
 
-    // Lookup installation
-    const octokit = new Octokit({ auth: appAuth.token })
-    const { data: installation } = await octokit.apps.getRepoInstallation({
-      owner,
-      repo,
-    })
+      // Lookup installation
+      const octokit = new Octokit({ auth: appAuth.token })
+      const { data: installation } = await octokit.apps.getRepoInstallation({
+        owner,
+        repo,
+      })
 
-    // Get installation token
-    const installationAuth = await auth({
-      type: "installation",
-      installationId: installation.id,
-    })
+      // Get installation token
+      const installationAuth = await auth({
+        type: "installation",
+        installationId: installation.id,
+      })
 
-    return c.json({ token: installationAuth.token })
+      return c.json({ token: installationAuth.token })
+    } catch (err) {
+      console.error("Failed to get installation token:", err)
+      const message = err instanceof Error ? err.message : "Failed to get installation token"
+      return c.json({ error: message }, { status: 500 })
+    }
   })
   /**
    * Used by the GitHub action to get GitHub installation access token given user PAT token (used when testing `opencode github run` locally)
diff --git a/packages/function/src/github-oidc.test.ts b/packages/function/src/github-oidc.test.ts
new file mode 100644
index 000000000000..ba39e5e56acd
--- /dev/null
+++ b/packages/function/src/github-oidc.test.ts
@@ -0,0 +1,32 @@
+import { describe, expect, test } from "bun:test"
+import { parseGithubOidcSub } from "./github-oidc"
+
+describe("parseGithubOidcSub", () => {
+  test("parses classic OIDC subject", () => {
+    expect(parseGithubOidcSub("repo:octocat/my-repo:ref:refs/heads/main")).toEqual({
+      owner: "octocat",
+      repo: "my-repo",
+    })
+  })
+
+  test("strips immutable owner and repo id suffixes", () => {
+    expect(parseGithubOidcSub("repo:octocat@123456/my-repo@456789:ref:refs/heads/main")).toEqual({
+      owner: "octocat",
+      repo: "my-repo",
+    })
+  })
+
+  test("parses job_workflow_ref style subjects", () => {
+    expect(
+      parseGithubOidcSub("repo:my-org/my-repo:job_workflow_ref:my-org/my-repo/.github/workflows/ci.yml@refs/heads/main"),
+    ).toEqual({
+      owner: "my-org",
+      repo: "my-repo",
+    })
+  })
+
+  test("throws on invalid subject", () => {
+    expect(() => parseGithubOidcSub("invalid")).toThrow("Invalid OIDC subject")
+    expect(() => parseGithubOidcSub("repo:only-owner")).toThrow("Invalid OIDC subject")
+  })
+})
diff --git a/packages/function/src/github-oidc.ts b/packages/function/src/github-oidc.ts
new file mode 100644
index 000000000000..78ee21c6236c
--- /dev/null
+++ b/packages/function/src/github-oidc.ts
@@ -0,0 +1,15 @@
+/**
+ * Parse repo owner/name from a GitHub Actions OIDC `sub` claim.
+ * Supports classic `repo:owner/name:...` and immutable
+ * `repo:owner@account_id/name@repo_id:...` subject claims.
+ */
+export function parseGithubOidcSub(sub: string) {
+  const repoPart = sub.split(":")[1]
+  if (!repoPart) throw new Error(`Invalid OIDC subject: ${sub}`)
+  const [rawOwner, rawRepo] = repoPart.split("/")
+  if (!rawOwner || !rawRepo) throw new Error(`Invalid OIDC subject: ${sub}`)
+  return {
+    owner: rawOwner.split("@")[0]!,
+    repo: rawRepo.split("@")[0]!,
+  }
+}
diff --git a/packages/opencode/src/cli/cmd/github.handler.ts b/packages/opencode/src/cli/cmd/github.handler.ts
index d55c0bf3fbfa..bde62ab0b2df 100644
--- a/packages/opencode/src/cli/cmd/github.handler.ts
+++ b/packages/opencode/src/cli/cmd/github.handler.ts
@@ -638,8 +638,16 @@ export const githubRun = Effect.fn("Cli.github.run")(function* (args: { event?:
         msg = e.message
       }
       if (isUserEvent) {
-        await createComment(`${msg}${footer()}`)
-        await removeReaction(commentType)
+        try {
+          await createComment(`${msg}${footer()}`)
+          await removeReaction(commentType)
+        } catch (commentError) {
+          // Token exchange may fail before octoRest is initialized
+          console.error(
+            "Failed to update GitHub comment/reaction:",
+            commentError instanceof Error ? commentError.message : commentError,
+          )
+        }
       }
       core.setFailed(msg)
       // Also output the clean error message for the action to capture
@@ -1001,12 +1009,19 @@ export const githubRun = Effect.fn("Cli.github.run")(function* (args: { event?:
             },
           })
 
+      const body = await response.text()
       if (!response.ok) {
-        const responseJson = (await response.json()) as { error?: string }
-        throw new Error(`App token exchange failed: ${response.status} ${response.statusText} - ${responseJson.error}`)
+        let detail = body
+        try {
+          const parsed = JSON.parse(body) as { error?: string }
+          if (parsed.error) detail = parsed.error
+        } catch {
+          // non-JSON error body from upstream
+        }
+        throw new Error(`App token exchange failed: ${response.status} ${response.statusText} - ${detail}`)
       }
 
-      const responseJson = (await response.json()) as { token: string }
+      const responseJson = JSON.parse(body) as { token: string }
       return responseJson.token
     }