fix: only scrub requests that target Claude models

README.md

@@ -69,9 +69,12 @@ Verify at `http://localhost:3456/plugins` — you should see `opencode-scrub` li
 | OhMyOpenCode/Sisyphus prompt | OMO identity line removed, `<omo-env>` block removed, "You are powered by..." line removed; persona rules preserved |
 | OpenCode prompt + user CLAUDE.md additions | identity stripped, all user content preserved |
 | OpenCode environment preamble + `<env>` | duplicate preamble and redundant fields removed; bare `Working directory` retained for Meridian's cwd extraction |
+| Request for a non-Claude model (e.g. `gpt-5.3-codex`) | unchanged |
 
 The plugin runs for the `opencode` adapter and for `passthrough` requests that still carry an OpenCode-specific identity or runtime marker. This covers OpenCode routed through LiteLLM when its client headers are removed. Other passthrough prompts, including genuine Claude Code prompts with an `<env>` block, remain byte-for-byte unchanged.
 
+Only requests that target a Claude model are scrubbed: Meridian's resolved aliases (`opus`, `sonnet`, `haiku`, `fable`, optionally with `[1m]`) and any model id containing `claude`. When Meridian serves another provider, such as OpenAI GPT/Codex models, the OpenCode prompt reaches that provider exactly as the client sent it.
+
 ## Rules
 
 The scrub applies 8 independent regex replacements, each idempotent and each a no-op when its pattern is absent:

src/__tests__/plugin.test.ts

@@ -47,3 +47,24 @@ describe("opencode-scrub adapter boundary", () => {
     expect(result?.systemContext).toContain("Working directory: /client/project")
   })
 })
+
+describe("opencode-scrub model boundary", () => {
+  const scrubbedWithoutModel = plugin.onRequest?.({ adapter: "opencode", systemContext: opencodePrompt, metadata: {} })
+
+  for (const model of ["opus", "opus[1m]", "sonnet", "sonnet[1m]", "haiku", "fable", "fable[1m]", "claude-opus-5-5", "anthropic/claude-sonnet-5"]) {
+    it(`scrubs requests for Claude model ${model}`, () => {
+      const ctx: RequestContext = { adapter: "opencode", model, systemContext: opencodePrompt, metadata: {} }
+      expect(plugin.onRequest?.(ctx)?.systemContext).toBe(scrubbedWithoutModel?.systemContext)
+    })
+  }
+
+  for (const adapter of ["opencode", "passthrough"]) {
+    for (const model of ["gpt-6-luna", "gpt-5.3-codex", "openai/gpt-5.5"]) {
+      it(`leaves ${adapter} requests for ${model} untouched`, () => {
+        const ctx: RequestContext = { adapter, model, systemContext: opencodePrompt, metadata: {} }
+        expect(plugin.onRequest?.(ctx)).toBe(ctx)
+        expect(ctx.systemContext).toBe(opencodePrompt)
+      })
+    }
+  }
+})

src/index.ts

@@ -18,6 +18,11 @@ export type { Transform, RequestContext } from "./types.js"
 const PASSTHROUGH_OPENCODE_MARKER =
   /You are OpenCode, the best coding agent on the planet\.|You are powered by the model named |<omo-env>|<agent-identity>|You are (?:"|\*\*)Sisyphus(?:"|\*\*)[^\n]*OhMyOpenCode/
 
+// Meridian resolves Claude requests to an SDK alias (`opus`, `sonnet[1m]`, ...)
+// before plugins run; full `claude-*` ids cover other callers. Requests for
+// other providers (e.g. OpenAI GPT/Codex models) keep their prompt as sent.
+const CLAUDE_MODEL = /claude|^(?:opus|sonnet|haiku|fable)(?:\[1m\])?$/i
+
 const plugin: Transform = {
   name: "opencode-scrub",
   version: packageMetadata.version,
@@ -26,6 +31,7 @@ const plugin: Transform = {
 
   onRequest(ctx: RequestContext): RequestContext {
     if (!ctx.systemContext) return ctx
+    if (ctx.model !== undefined && !CLAUDE_MODEL.test(ctx.model)) return ctx
     if (ctx.adapter === "passthrough" && !PASSTHROUGH_OPENCODE_MARKER.test(ctx.systemContext)) return ctx
     const scrubbed = scrubOpencodeFingerprints(ctx.systemContext)
     if (scrubbed === ctx.systemContext) return ctx

src/types.ts

@@ -15,6 +15,8 @@
 export interface RequestContext {
   /** Agent adapter name (readonly from meridian's perspective) */
   readonly adapter: string
+  /** Model the request targets, as resolved by meridian */
+  model?: string
   /** Client-provided system prompt / context string, if any */
   systemContext?: string
   /** Plugin-to-plugin state bag */