refactor(opencode): extract session LLM request prep (anomalyco#28560)

Author: kitlangton

packages/opencode/src/session/llm.ts

@@ -212,39 +212,8 @@ const live: Layer.Layer<
           })
         : undefined
 
-      l.info("params", {
-        temperature: params.temperature,
-        topP: params.topP,
-        topK: params.topK,
-        maxOutputTokens: params.maxOutputTokens,
-        variant: input.user.model.variant,
-        providerOptions: ProviderTransform.providerOptions(input.model, params.options),
-        limit: input.model.limit,
-        capabilities: input.model.capabilities,
-      })
-
-      const opencodeProjectID = input.model.providerID.startsWith("opencode")
-        ? (yield* InstanceState.context).project.id
-        : undefined
-
-      const requestHeaders = {
-        ...(input.model.providerID.startsWith("opencode")
-          ? {
-              ...(opencodeProjectID ? { "x-opencode-project": opencodeProjectID } : {}),
-              "x-opencode-session": input.sessionID,
-              "x-opencode-request": input.user.id,
-              "x-opencode-client": flags.client,
-              "User-Agent": `opencode/${InstallationVersion}`,
-            }
-          : {
-              "x-session-affinity": input.sessionID,
-              ...(input.parentSessionID ? { "x-parent-session-id": input.parentSessionID } : {}),
-              "User-Agent": `opencode/${InstallationVersion}`,
-            }),
-        ...input.model.headers,
-        ...headers,
-      }
-
+      // Runtime seam: native is an opt-in adapter over @opencode-ai/llm. It
+      // either returns a ready LLMEvent stream or a concrete fallback reason.
       if (flags.experimentalNativeLlm) {
         const native = LLMNativeRuntime.stream({
           model: input.model,