feat: Add Dify model provider with conversation ID management

packages/opencode/src/provider/provider.ts

@@ -588,6 +588,15 @@ export namespace Provider {
         },
       }
     },
+    dify: async () => {
+      const difyLog = Log.create({ service: "dify" })
+      return {
+        autoload: false,
+        async getModel(sdk: any, modelID: string, options?: Record<string, any>) {
+          return (sdk as any)(modelID, { ...options, logger: difyLog })
+        },
+      }
+    },
   }
 
   export const Model = z

packages/opencode/src/session/dify-headers.ts

@@ -0,0 +1,85 @@
+import { Config } from "@/config/config"
+import { Session } from "@/session"
+import type { Provider } from "@/provider/provider"
+import type { Agent } from "@/agent/agent"
+import type { MessageV2 } from "./message-v2"
+
+export type DifyPartMetadata = {
+  difyWorkflowData?: { conversationId?: string }
+}
+
+function findLastCompactionIndex(msgs: MessageV2.WithParts[]): number | undefined {
+  for (let i = msgs.length - 1; i >= 0; i--) {
+    const info = msgs[i].info
+    if (
+      info.role === "assistant" &&
+      (info.summary === true || info.mode === "compaction" || info.agent === "compaction")
+    ) {
+      return i
+    }
+  }
+  return undefined
+}
+
+function findConversationId(msgs: MessageV2.WithParts[]): string | undefined {
+  for (let i = msgs.length - 1; i >= 0; i--) {
+    const msg = msgs[i]
+    if (msg.info.role !== "assistant") continue
+
+    for (const part of msg.parts) {
+      if ("metadata" in part && part.metadata) {
+        const meta = part.metadata as DifyPartMetadata
+        if (meta.difyWorkflowData?.conversationId) {
+          return meta.difyWorkflowData.conversationId
+        }
+      }
+    }
+  }
+  return undefined
+}
+
+export type ApplyDifyHeadersOptions = {
+  headers: Record<string, string>
+  provider: Provider.Info
+  model: Provider.Model
+  agent: Agent.Info
+  sessionID: string
+  user: MessageV2.User
+}
+
+export async function applyDifyHeaders(opts: ApplyDifyHeadersOptions): Promise<void> {
+  const { headers: h, sessionID, user } = opts
+  const currentUserId = user.id
+  const providerOptions = opts.provider.options?.headers
+  const modelHeaders = opts.model.headers ?? {}
+  const isCompactionRequest = opts.agent.name === "compaction"
+
+  Object.assign(h, providerOptions ?? {}, modelHeaders)
+  if (!h["user-id"]) {
+    const config = await Config.get()
+    h["user-id"] = config.username ?? "unknown"
+  }
+
+  const msgs = await Session.messages({ sessionID, limit: 100 })
+  const compactionIndex = findLastCompactionIndex(msgs)
+  const conversationId = findConversationId(msgs)
+
+  if (compactionIndex === undefined || compactionIndex !== msgs.length - 3) {
+    if (conversationId) h["chat-id"] = conversationId
+    return
+  }
+
+  const isCurrentSynthetic = (opts.user as any).parts?.some((p: any) => p.type === "text" && p.synthetic) ?? false
+
+  /**
+   * Determines if we should reset the chat-id (start a new conversation).
+   * - true: Normal request after compaction/summary with a real (non-synthetic) user message.
+   *   In this case, do NOT set chat-id to avoid inheriting old conversation.
+   * - false: Compaction request OR synthetic user message → preserve existing chat-id.
+   */
+  const shouldResetChatId = !isCompactionRequest && !isCurrentSynthetic
+
+  if (!shouldResetChatId && conversationId) {
+    h["chat-id"] = conversationId
+  }
+}

packages/opencode/src/session/llm.ts

@@ -1,6 +1,7 @@
 import { Installation } from "@/installation"
 import { Provider } from "@/provider/provider"
 import { Log } from "@/util/log"
+import { applyDifyHeaders } from "./dify-headers"
 import {
   streamText,
   wrapLanguageModel,
@@ -144,6 +145,17 @@ export namespace LLM {
       },
     )
 
+    if (input.model.providerID === "dify") {
+      await applyDifyHeaders({
+        headers: headers as Record<string, string>,
+        provider,
+        model: input.model,
+        agent: input.agent,
+        sessionID: input.sessionID,
+        user: input.user,
+      })
+    }
+
     const maxOutputTokens =
       isCodex || provider.id.includes("github-copilot") ? undefined : ProviderTransform.maxOutputTokens(input.model)