fix: sanitize malformed agent frontmatter

packages/opencode/src/config/markdown.ts

@@ -17,11 +17,10 @@ export function shell(template: string) {
 // other coding agents like claude code allow invalid yaml in their
 // frontmatter, we need to fallback to a more permissive parser for those cases
 export function fallbackSanitization(content: string): string {
-  const match = content.match(/^---\r?\n([\s\S]*?)\r?\n---/)
+  const match = content.match(/^---(\r?\n)([\s\S]*?)(\r?\n)?^---[ \t]*(\r?\n|$)/m)
   if (!match) return content
 
-  const frontmatter = match[1]
-  const lines = frontmatter.split(/\r?\n/)
+  const lines = match[2].split(/\r?\n/)
   const result: string[] = []
 
   for (const line of lines) {
@@ -63,15 +62,18 @@ export function fallbackSanitization(content: string): string {
     result.push(line)
   }
 
-  const processed = result.join("\n")
-  return content.replace(frontmatter, () => processed)
+  const processed = result.join(match[1])
+  return content.replace(match[0], () => `---${match[1]}${processed}${match[3] ?? ""}---${match[4]}`)
 }
 
 export async function parse(filePath: string) {
   const template = await Filesystem.readText(filePath)
 
   try {
     const md = matter(template)
+    const sanitized = fallbackSanitization(template)
+    // Retry sanitized frontmatter when gray-matter silently treated it as content.
+    if (Object.keys(md.data).length === 0 && sanitized !== template) return matter(sanitized)
     return md
   } catch {
     try {

packages/opencode/test/config/fixtures/colon-in-value.md

@@ -0,0 +1,16 @@
+---
+description: Reviews changes: returns a verdict.
+mode: subagent
+hidden: true
+model: anthropic/claude-sonnet-4-5
+temperature: 0.2
+steps: 7
+permission:
+  read: allow
+  bash:
+    npm test: allow
+    rm -rf *: deny
+--- 
+You are the code review agent.
+
+Review the full diff and return a concise verdict.

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

@@ -1,5 +1,9 @@
 import { expect, test, describe } from "bun:test"
+import path from "path"
+import { mkdir } from "fs/promises"
+import { ConfigAgent } from "@/config/agent"
 import { ConfigMarkdown } from "@/config/markdown"
+import { tmpdir } from "../fixture/fixture"
 
 describe("ConfigMarkdown: normal template", () => {
   const template = `This is a @valid/path/to/a/file and it should also match at
@@ -226,3 +230,67 @@ describe("ConfigMarkdown: frontmatter has weird model id", async () => {
     expect(result.content.trim()).toBe("Strictly follow da rules")
   })
 })
+
+describe("ConfigMarkdown: frontmatter with colon in value followed by other fields", async () => {
+  const result = await ConfigMarkdown.parse(import.meta.dir + "/fixtures/colon-in-value.md")
+
+  test("should preserve full description including colons", () => {
+    expect(result.data.description).toBe("Reviews changes: returns a verdict.")
+  })
+
+  test("should preserve subsequent mode field", () => {
+    expect(result.data.mode).toBe("subagent")
+  })
+
+  test("should preserve hidden field", () => {
+    expect(result.data.hidden).toBe(true)
+  })
+
+  test("should preserve model field", () => {
+    expect(result.data.model).toBe("anthropic/claude-sonnet-4-5")
+  })
+
+  test("should preserve temperature field", () => {
+    expect(result.data.temperature).toBe(0.2)
+  })
+
+  test("should preserve steps field", () => {
+    expect(result.data.steps).toBe(7)
+  })
+
+  test("should preserve nested permission fields", () => {
+    expect(result.data.permission.read).toBe("allow")
+    expect(result.data.permission.bash["npm test"]).toBe("allow")
+    expect(result.data.permission.bash["rm -rf *"]).toBe("deny")
+  })
+
+  test("should preserve body content", () => {
+    expect(result.content.trim()).toStartWith("You are the code review agent.")
+  })
+
+  test("should load colon in value config through ConfigAgent", async () => {
+    await using tmp = await tmpdir({
+      init: async (dir) => {
+        await mkdir(path.join(dir, "agent"))
+        await Bun.write(
+          path.join(dir, "agent", "code-reviewer.md"),
+          await Bun.file(import.meta.dir + "/fixtures/colon-in-value.md").text(),
+        )
+      },
+    })
+
+    const agent = (await ConfigAgent.load(tmp.path))["code-reviewer"]
+    if (!agent) throw new Error("Expected code-reviewer agent to load")
+    expect(agent.description).toBe("Reviews changes: returns a verdict.")
+    expect(agent.mode).toBe("subagent")
+    expect(agent.hidden).toBe(true)
+    expect(agent.prompt).toStartWith("You are the code review agent.")
+    expect(agent.prompt).not.toContain("---")
+    if (!agent.permission) throw new Error("Expected code-reviewer agent permissions to load")
+    expect(agent.permission.read).toBe("allow")
+    expect(agent.permission.bash).toEqual({
+      "npm test": "allow",
+      "rm -rf *": "deny",
+    })
+  })
+})