Method handlePartDelta

packages/opencode/src/acp/event.ts:154–199

(event: EventMessagePartDelta)

  }

  private async handlePartDelta(event: EventMessagePartDelta) {
    const props = event.properties
    const session = await Effect.runPromise(this.input.session.tryGet(props.sessionID))
    if (!session) return

    const known = await Effect.runPromise(
      this.input.session.tryGetPartMetadata({
        sessionId: session.id,
        messageId: props.messageID,
        partId: props.partID,
      }),
    )
    const metadata =
      known?.role && known.partType
        ? known
        : await this.fetchPartMetadata(session.id, session.cwd, props.messageID, props.partID)
    if (metadata?.role !== "assistant") return
    if (metadata.partType === "text" && props.field === "text" && metadata.ignored !== true) {
      await this.input.connection.sessionUpdate({
        sessionId: session.id,
        update: {
          sessionUpdate: "agent_message_chunk",
          messageId: props.messageID,
          content: {
            type: "text",
            text: props.delta,
          },
        },
      })
      return
    }

    if (metadata.partType === "reasoning" && props.field === "text") {
      await this.input.connection.sessionUpdate({
        sessionId: session.id,
        update: {
          sessionUpdate: "agent_thought_chunk",
          messageId: props.messageID,
          content: {
            type: "text",
            text: props.delta,
          },
        },
      })
    }
  }

  private async fetchPartMetadata(sessionId: string, cwd: string, messageId: string, partId: string) {
    const message = await this.input.sdk.session