Merge plugin system prompts for provider compatibility

apps/server/package.json

@@ -10,7 +10,7 @@
     "dev": "OPENWORK_DEV_MODE=1 bun src/cli.ts",
     "test": "bun test",
     "test:artifacts": "bun test src/artifact-files.e2e.test.ts src/workspace-init.test.ts src/server.normalizeWorkspaceRelativePath.test.ts",
-    "build": "tsc -p tsconfig.json && bun build src/opencode-plugins/openwork-extensions-preview.ts src/opencode-plugins/openwork-capabilities-knowledge.ts src/opencode-plugins/openwork-anthropic-adaptive-thinking.ts src/opencode-plugins/openwork-anthropic-tool-schema.ts --outdir dist/opencode-plugins --target node --format esm",
+    "build": "tsc -p tsconfig.json && bun build src/opencode-plugins/openwork-extensions-preview.ts src/opencode-plugins/openwork-capabilities-knowledge.ts src/opencode-plugins/openwork-anthropic-adaptive-thinking.ts src/opencode-plugins/openwork-anthropic-tool-schema.ts src/opencode-plugins/openwork-system-prompt-normalizer.ts --outdir dist/opencode-plugins --target node --format esm",
     "build:bin": "bun build --compile src/cli.ts --outfile dist/bin/openwork-server",
     "build:bin:all": "bun ./script/build.ts --outdir dist/bin --target bun-darwin-arm64 --target bun-darwin-x64 --target bun-linux-x64 --target bun-linux-arm64 --target bun-windows-x64",
     "start": "bun dist/cli.js",

apps/server/src/opencode-plugins/openwork-capabilities-knowledge.test.ts

@@ -3,6 +3,23 @@ import { resolve } from "node:path";
 import { OpenWorkCapabilitiesKnowledge } from "./openwork-capabilities-knowledge.js";
 
 describe("OpenWork capabilities knowledge plugin", () => {
+  test("adds capabilities knowledge to the system prompt", async () => {
+    const plugin = await OpenWorkCapabilitiesKnowledge();
+    const output = {
+      system: [
+        "You are OpenWork.",
+        "",
+      ],
+    };
+
+    await plugin["experimental.chat.system.transform"]({}, output);
+
+    expect(output.system).toHaveLength(3);
+    expect(output.system[0]).toBe("You are OpenWork.");
+    expect(output.system[2]).toContain("You are running inside OpenWork");
+    expect(output.system[2]).toContain("OpenWork product questions");
+  });
+
   test("retrieves Slack connection guidance from bundled docs", async () => {
     process.env.OPENWORK_DOCS_DIR = resolve(import.meta.dir, "../../../../packages/docs");
 

apps/server/src/opencode-plugins/openwork-capabilities-knowledge.ts

@@ -214,6 +214,13 @@ function excerpt(content: string, query: string): string {
 export const OpenWorkCapabilitiesKnowledge = async () => ({
   "experimental.chat.system.transform": async (_input: unknown, output: { system: string[] }) => {
     output.system.push(OPENWORK_CAPABILITIES_KNOWLEDGE);
+
+    // Strict OpenAI-compatible proxies reject multiple system messages.
+    // Keep the knowledge, but send it as one provider-safe system prompt.
+    // Mutate the array in-place to ensure the framework sees the change
+    const merged = output.system.filter((entry) => entry.trim().length > 0).join("\n\n");
+    output.system.length = 0;
+    if (merged) output.system.push(merged);
   },
   tool: {
     openwork_docs_search: {

apps/server/src/opencode-plugins/openwork-extensions-preview.test.ts

@@ -0,0 +1,18 @@
+import { describe, expect, test } from "bun:test";
+import { OpenWorkExtensionsPreview } from "./openwork-extensions-preview.js";
+
+describe("OpenWork extensions preview plugin", () => {
+  test("adds extension guidance to the system prompt", async () => {
+    const plugin = await OpenWorkExtensionsPreview();
+    const output = {
+      system: ["You are a title generator.", ""],
+    };
+
+    await plugin["experimental.chat.system.transform"]({}, output);
+
+    expect(output.system).toHaveLength(4);
+    expect(output.system[0]).toBe("You are a title generator.");
+    expect(output.system[2]).toContain("check OpenWork extensions");
+    expect(output.system[3]).toContain("openwork_ui_execute_action");
+  });
+});

apps/server/src/opencode-plugins/openwork-extensions-preview.ts

@@ -204,6 +204,13 @@ export const OpenWorkExtensionsPreview = async () => ({
   "experimental.chat.system.transform": async (_input: unknown, output: { system: string[] }) => {
     output.system.push(OPENWORK_EXTENSION_DISCOVERY_INSTRUCTION);
     output.system.push(OPENWORK_UI_CONTROL_INSTRUCTION);
+
+    // Strict OpenAI-compatible proxies reject multiple system messages.
+    // Keep the guidance, but send it as one provider-safe system prompt.
+    // Mutate the array in-place to ensure the framework sees the change
+    const merged = output.system.filter((entry) => entry.trim().length > 0).join("\n\n");
+    output.system.length = 0;
+    if (merged) output.system.push(merged);
   },
   tool: {
     openwork_extension_list_actions: {

apps/server/src/opencode-plugins/openwork-system-prompt-normalizer.test.ts

@@ -0,0 +1,37 @@
+import { describe, expect, test } from "bun:test";
+import { OpenWorkCapabilitiesKnowledge } from "./openwork-capabilities-knowledge.js";
+import { OpenWorkExtensionsPreview } from "./openwork-extensions-preview.js";
+import { mergeSystemPromptsInPlace, OpenWorkSystemPromptNormalizer } from "./openwork-system-prompt-normalizer.js";
+
+describe("OpenWork system prompt normalizer", () => {
+  test("merges multiple system prompts in place", () => {
+    const system = [" base prompt ", "", " plugin prompt "];
+    const original = system;
+
+    mergeSystemPromptsInPlace(system);
+
+    expect(system).toBe(original);
+    expect(system).toEqual(["base prompt\n\nplugin prompt"]);
+  });
+
+  test("runs after OpenWork plugin transforms to produce one provider-safe system prompt", async () => {
+    const capabilities = await OpenWorkCapabilitiesKnowledge();
+    const extensions = await OpenWorkExtensionsPreview();
+    const normalizer = await OpenWorkSystemPromptNormalizer();
+    const output = {
+      system: ["You are OpenWork.", ""],
+    };
+
+    await capabilities["experimental.chat.system.transform"]({}, output);
+    await extensions["experimental.chat.system.transform"]({}, output);
+    expect(output.system.length).toBeGreaterThan(1);
+
+    await normalizer["experimental.chat.system.transform"]({}, output);
+
+    expect(output.system).toHaveLength(1);
+    expect(output.system[0]).toContain("You are OpenWork.");
+    expect(output.system[0]).toContain("You are running inside OpenWork");
+    expect(output.system[0]).toContain("check OpenWork extensions");
+    expect(output.system[0]).toContain("openwork_ui_execute_action");
+  });
+});

apps/server/src/opencode-plugins/openwork-system-prompt-normalizer.ts

@@ -0,0 +1,20 @@
+type SystemTransformOutput = {
+  system: string[];
+};
+
+export function mergeSystemPromptsInPlace(system: string[]): void {
+  const merged = system
+    .map((entry) => entry.trim())
+    .filter(Boolean)
+    .join("\n\n");
+
+  // Keep the same array reference for hook callers that hold onto it.
+  system.length = 0;
+  if (merged) system.push(merged);
+}
+
+export const OpenWorkSystemPromptNormalizer = async () => ({
+  "experimental.chat.system.transform": async (_input: unknown, output: SystemTransformOutput) => {
+    mergeSystemPromptsInPlace(output.system);
+  },
+});

apps/server/src/openwork-extensions-plugin-path.ts

@@ -27,5 +27,6 @@ export function openworkPluginPath(name: string, here = dirname(fileURLToPath(im
 
 export const openworkExtensionsPreviewPluginPath = () => openworkPluginPath("openwork-extensions-preview");
 export const openworkCapabilitiesKnowledgePluginPath = () => openworkPluginPath("openwork-capabilities-knowledge");
+export const openworkSystemPromptNormalizerPluginPath = () => openworkPluginPath("openwork-system-prompt-normalizer");
 export const openworkAnthropicAdaptiveThinkingPluginPath = () => openworkPluginPath("openwork-anthropic-adaptive-thinking");
 export const openworkAnthropicToolSchemaPluginPath = () => openworkPluginPath("openwork-anthropic-tool-schema");

apps/server/src/openwork-runtime-config.ts

@@ -18,6 +18,7 @@ import { randomUUID } from "node:crypto";
 import {
   openworkExtensionsPreviewPluginPath,
   openworkCapabilitiesKnowledgePluginPath,
+  openworkSystemPromptNormalizerPluginPath,
   openworkAnthropicAdaptiveThinkingPluginPath,
   openworkAnthropicToolSchemaPluginPath,
 } from "./openwork-extensions-plugin-path.js";
@@ -89,6 +90,7 @@ export async function buildOpenworkRuntimeConfigObject(
       openworkAnthropicAdaptiveThinkingPluginPath(),
       openworkAnthropicToolSchemaPluginPath(),
       ...runtimePluginList(runtimeConfig),
+      openworkSystemPromptNormalizerPluginPath(),
     ],
     ...(disabledProviders.length ? { disabled_providers: disabledProviders } : {}),
     mcp: runtimeMcpMap(runtimeConfig),