fix(converters): OpenCode subagent model and FQ agent name resolution (#483)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/converters/claude-to-opencode.ts

@@ -93,7 +93,11 @@ function convertAgent(agent: ClaudeAgent, options: ClaudeToOpenCodeOptions) {
     mode: options.agentMode,
   }
 
-  if (agent.model && agent.model !== "inherit") {
+  // Only write model for primary agents. Subagents inherit from the parent
+  // session, making them provider-agnostic. Writing an explicit model like
+  // "anthropic/claude-haiku-4-5" on a subagent causes ProviderModelNotFoundError
+  // when the user's OpenCode env uses a different provider. See #477.
+  if (agent.model && agent.model !== "inherit" && options.agentMode === "primary") {
     frontmatter.model = normalizeModelWithProvider(agent.model)
   }
 
@@ -261,6 +265,30 @@ function rewriteClaudePaths(body: string): string {
     .replace(/\.claude\//g, ".opencode/")
 }
 
+/**
+ * Transform skill/agent content for OpenCode compatibility.
+ * Composes path rewriting with fully-qualified agent name flattening.
+ *
+ * OpenCode resolves agents by flat filename, so 3-segment FQ references
+ * like `compound-engineering:document-review:coherence-reviewer` must be
+ * rewritten to just `coherence-reviewer`. 2-segment skill references
+ * (e.g. `compound-engineering:document-review`) are left unchanged.
+ * See #477.
+ */
+export function transformSkillContentForOpenCode(body: string): string {
+  let result = rewriteClaudePaths(body)
+  // Rewrite 3-segment FQ agent refs: plugin:category:agent-name -> agent-name.
+  // Boundary assertions prevent partial matching on 4+ segment names
+  // (e.g. `a:b:c:d` would otherwise produce `c:d` or `a:d`).
+  // The `/` in the lookbehind prevents rewriting slash commands like
+  // `/team:ops:deploy` — agent names are never preceded by `/`.
+  result = result.replace(
+    /(?<![a-z0-9:/-])[a-z][a-z0-9-]*:[a-z][a-z0-9-]*:([a-z][a-z0-9-]*)(?![a-z0-9:-])/g,
+    "$1",
+  )
+  return result
+}
+
 function inferTemperature(agent: ClaudeAgent): number | undefined {
   const sample = `${agent.name} ${agent.description ?? ""}`.toLowerCase()
   if (/(review|audit|security|sentinel|oracle|lint|verification|guardian)/.test(sample)) {

src/targets/opencode.ts

@@ -1,5 +1,6 @@
 import path from "path"
-import { backupFile, copyDir, ensureDir, pathExists, readJson, resolveCommandPath, sanitizePathName, writeJson, writeText } from "../utils/files"
+import { backupFile, copySkillDir, ensureDir, pathExists, readJson, resolveCommandPath, sanitizePathName, writeJson, writeText } from "../utils/files"
+import { transformSkillContentForOpenCode } from "../converters/claude-to-opencode"
 import type { OpenCodeBundle, OpenCodeConfig } from "../types/opencode"
 
 // Merges plugin config into existing opencode.json. User keys win on conflict. See ADR-002.
@@ -100,7 +101,12 @@ export async function writeOpenCodeBundle(outputRoot: string, bundle: OpenCodeBu
   if (bundle.skillDirs.length > 0) {
     const skillsRoot = openCodePaths.skillsDir
     for (const skill of bundle.skillDirs) {
-      await copyDir(skill.sourceDir, path.join(skillsRoot, sanitizePathName(skill.name)))
+      await copySkillDir(
+        skill.sourceDir,
+        path.join(skillsRoot, sanitizePathName(skill.name)),
+        transformSkillContentForOpenCode,
+        true, // transform all .md files — FQ agent names appear in references too
+      )
     }
   }
 }

src/utils/files.ts

@@ -116,14 +116,20 @@ export async function copyDir(sourceDir: string, targetDir: string): Promise<voi
 }
 
 /**
- * Copy a skill directory, optionally transforming SKILL.md content.
- * All other files are copied verbatim. Used by target writers to apply
+ * Copy a skill directory, optionally transforming markdown content.
+ * Non-markdown files are copied verbatim. Used by target writers to apply
  * platform-specific content transforms to pass-through skills.
+ *
+ * By default only SKILL.md is transformed (safe for slash-command rewrites
+ * that shouldn't touch reference files). Set `transformAllMarkdown` to also
+ * transform reference .md files — needed when the transform rewrites content
+ * that appears in reference files (e.g. fully-qualified agent names).
  */
 export async function copySkillDir(
   sourceDir: string,
   targetDir: string,
   transformSkillContent?: (content: string) => string,
+  transformAllMarkdown?: boolean,
 ): Promise<void> {
   await ensureDir(targetDir)
   const entries = await fs.readdir(sourceDir, { withFileTypes: true })
@@ -133,9 +139,12 @@ export async function copySkillDir(
     const targetPath = path.join(targetDir, entry.name)
 
     if (entry.isDirectory()) {
-      await copySkillDir(sourcePath, targetPath, transformSkillContent)
+      await copySkillDir(sourcePath, targetPath, transformSkillContent, transformAllMarkdown)
     } else if (entry.isFile()) {
-      if (entry.name === "SKILL.md" && transformSkillContent) {
+      const shouldTransform = transformSkillContent && (
+        entry.name === "SKILL.md" || (transformAllMarkdown && entry.name.endsWith(".md"))
+      )
+      if (shouldTransform) {
         const content = await readText(sourcePath)
         await writeText(targetPath, transformSkillContent(content))
       } else {