refactor: centralize skills prompt resolution

docs/concepts/system-prompt.md

@@ -15,7 +15,7 @@ The prompt is assembled by Clawdbot and injected into each agent run.
 The prompt is intentionally compact and uses fixed sections:
 
 - **Tooling**: current tool list + short descriptions.
-- **Skills**: tells the model how to load skill instructions on demand.
+- **Skills** (when available): tells the model how to load skill instructions on demand.
 - **Clawdbot Self-Update**: how to run `config.apply` and `update.run`.
 - **Workspace**: working directory (`agents.defaults.workspace`).
 - **Workspace Files (injected)**: indicates bootstrap files are included below.
@@ -52,7 +52,8 @@ Use `agents.defaults.userTimezone` in `~/.clawdbot/clawdbot.json` to change the
 When eligible skills exist, Clawdbot injects a compact **available skills list**
 (`formatSkillsForPrompt`) that includes the **file path** for each skill. The
 prompt instructs the model to use `read` to load the SKILL.md at the listed
-location (workspace, managed, or bundled).
+location (workspace, managed, or bundled). If no skills are eligible, the
+Skills section is omitted.
 
 ```
 <available_skills>

src/agents/pi-embedded-runner.test.ts

@@ -6,11 +6,9 @@ import {
   applyGoogleTurnOrderingFix,
   buildEmbeddedSandboxInfo,
   createSystemPromptOverride,
-  resolveSkillsPrompt,
   splitSdkTools,
 } from "./pi-embedded-runner.js";
 import type { SandboxContext } from "./sandbox.js";
-import type { SkillEntry } from "./skills.js";
 
 describe("buildEmbeddedSandboxInfo", () => {
   it("returns undefined when sandbox is missing", () => {
@@ -124,35 +122,6 @@ describe("createSystemPromptOverride", () => {
   });
 });
 
-describe("resolveSkillsPrompt", () => {
-  it("prefers snapshot prompt when available", () => {
-    const prompt = resolveSkillsPrompt({
-      skillsSnapshot: { prompt: "SNAPSHOT", skills: [] },
-      workspaceDir: "/tmp/clawd",
-    });
-    expect(prompt).toBe("SNAPSHOT");
-  });
-
-  it("builds prompt from entries when snapshot is missing", () => {
-    const entry: SkillEntry = {
-      skill: {
-        name: "demo-skill",
-        description: "Demo",
-        filePath: "/app/skills/demo-skill/SKILL.md",
-        baseDir: "/app/skills/demo-skill",
-        source: "clawdbot-bundled",
-      },
-      frontmatter: {},
-    };
-    const prompt = resolveSkillsPrompt({
-      skillEntries: [entry],
-      workspaceDir: "/tmp/clawd",
-    });
-    expect(prompt).toContain("<available_skills>");
-    expect(prompt).toContain("/app/skills/demo-skill/SKILL.md");
-  });
-});
-
 describe("applyGoogleTurnOrderingFix", () => {
   const makeAssistantFirst = () =>
     [

src/agents/pi-embedded-runner.ts

@@ -89,9 +89,8 @@ import { resolveSandboxContext } from "./sandbox.js";
 import {
   applySkillEnvOverrides,
   applySkillEnvOverridesFromSnapshot,
-  buildWorkspaceSkillsPrompt,
   loadWorkspaceSkillEntries,
-  type SkillEntry,
+  resolveSkillsPromptForRun,
   type SkillSnapshot,
 } from "./skills.js";
 import { buildAgentSystemPrompt } from "./system-prompt.js";
@@ -622,24 +621,6 @@ export function createSystemPromptOverride(
   return () => trimmed;
 }
 
-export function resolveSkillsPrompt(params: {
-  skillsSnapshot?: SkillSnapshot;
-  skillEntries?: SkillEntry[];
-  config?: ClawdbotConfig;
-  workspaceDir: string;
-}): string {
-  const snapshotPrompt = params.skillsSnapshot?.prompt?.trim();
-  if (snapshotPrompt) return snapshotPrompt;
-  if (params.skillEntries && params.skillEntries.length > 0) {
-    const prompt = buildWorkspaceSkillsPrompt(params.workspaceDir, {
-      entries: params.skillEntries,
-      config: params.config,
-    });
-    return prompt.trim() ? prompt : "";
-  }
-  return "";
-}
-
 // Tool names are now capitalized (Bash, Read, Write, Edit) to bypass Anthropic's
 // OAuth token blocking of lowercase names. However, pi-coding-agent's SDK has
 // hardcoded lowercase names in its built-in tool registry, so we must pass ALL
@@ -866,9 +847,9 @@ export async function compactEmbeddedPiSession(params: {
               skills: skillEntries ?? [],
               config: params.config,
             });
-        const skillsPrompt = resolveSkillsPrompt({
+        const skillsPrompt = resolveSkillsPromptForRun({
           skillsSnapshot: params.skillsSnapshot,
-          skillEntries: shouldLoadSkillEntries ? skillEntries : undefined,
+          entries: shouldLoadSkillEntries ? skillEntries : undefined,
           config: params.config,
           workspaceDir: effectiveWorkspace,
         });
@@ -1196,9 +1177,9 @@ export async function runEmbeddedPiAgent(params: {
                 skills: skillEntries ?? [],
                 config: params.config,
               });
-          const skillsPrompt = resolveSkillsPrompt({
+          const skillsPrompt = resolveSkillsPromptForRun({
             skillsSnapshot: params.skillsSnapshot,
-            skillEntries: shouldLoadSkillEntries ? skillEntries : undefined,
+            entries: shouldLoadSkillEntries ? skillEntries : undefined,
             config: params.config,
             workspaceDir: effectiveWorkspace,
           });

src/agents/skills.test.ts

@@ -10,6 +10,8 @@ import {
   buildWorkspaceSkillSnapshot,
   buildWorkspaceSkillsPrompt,
   loadWorkspaceSkillEntries,
+  resolveSkillsPromptForRun,
+  type SkillEntry,
   syncSkillsToWorkspace,
 } from "./skills.js";
 import { buildWorkspaceSkillStatus } from "./skills-status.js";
@@ -404,6 +406,35 @@ describe("buildWorkspaceSkillsPrompt", () => {
   });
 });
 
+describe("resolveSkillsPromptForRun", () => {
+  it("prefers snapshot prompt when available", () => {
+    const prompt = resolveSkillsPromptForRun({
+      skillsSnapshot: { prompt: "SNAPSHOT", skills: [] },
+      workspaceDir: "/tmp/clawd",
+    });
+    expect(prompt).toBe("SNAPSHOT");
+  });
+
+  it("builds prompt from entries when snapshot is missing", () => {
+    const entry: SkillEntry = {
+      skill: {
+        name: "demo-skill",
+        description: "Demo",
+        filePath: "/app/skills/demo-skill/SKILL.md",
+        baseDir: "/app/skills/demo-skill",
+        source: "clawdbot-bundled",
+      },
+      frontmatter: {},
+    };
+    const prompt = resolveSkillsPromptForRun({
+      entries: [entry],
+      workspaceDir: "/tmp/clawd",
+    });
+    expect(prompt).toContain("<available_skills>");
+    expect(prompt).toContain("/app/skills/demo-skill/SKILL.md");
+  });
+});
+
 describe("loadWorkspaceSkillEntries", () => {
   it("handles an empty managed skills dir without throwing", async () => {
     const workspaceDir = await fs.mkdtemp(path.join(os.tmpdir(), "clawdbot-"));

src/agents/skills.ts

@@ -610,6 +610,24 @@ export function buildWorkspaceSkillsPrompt(
   return formatSkillsForPrompt(eligible.map((entry) => entry.skill));
 }
 
+export function resolveSkillsPromptForRun(params: {
+  skillsSnapshot?: SkillSnapshot;
+  entries?: SkillEntry[];
+  config?: ClawdbotConfig;
+  workspaceDir: string;
+}): string {
+  const snapshotPrompt = params.skillsSnapshot?.prompt?.trim();
+  if (snapshotPrompt) return snapshotPrompt;
+  if (params.entries && params.entries.length > 0) {
+    const prompt = buildWorkspaceSkillsPrompt(params.workspaceDir, {
+      entries: params.entries,
+      config: params.config,
+    });
+    return prompt.trim() ? prompt : "";
+  }
+  return "";
+}
+
 export function loadWorkspaceSkillEntries(
   workspaceDir: string,
   opts?: {

src/agents/system-prompt.test.ts

@@ -83,9 +83,11 @@ describe("buildAgentSystemPrompt", () => {
     expect(prompt).toContain("update.run");
   });
 
-  it("includes skills guidance with workspace path", () => {
+  it("includes skills guidance when skills prompt is present", () => {
     const prompt = buildAgentSystemPrompt({
       workspaceDir: "/tmp/clawd",
+      skillsPrompt:
+        "<available_skills>\n  <skill>\n    <name>demo</name>\n  </skill>\n</available_skills>",
     });
 
     expect(prompt).toContain("## Skills");
@@ -105,6 +107,15 @@ describe("buildAgentSystemPrompt", () => {
     expect(prompt).toContain("<name>demo</name>");
   });
 
+  it("omits skills section when no skills prompt is provided", () => {
+    const prompt = buildAgentSystemPrompt({
+      workspaceDir: "/tmp/clawd",
+    });
+
+    expect(prompt).not.toContain("## Skills");
+    expect(prompt).not.toContain("<available_skills>");
+  });
+
   it("renders project context files when provided", () => {
     const prompt = buildAgentSystemPrompt({
       workspaceDir: "/tmp/clawd",

src/agents/system-prompt.ts

@@ -139,6 +139,14 @@ export function buildAgentSystemPrompt(params: {
     runtimeProvider === "telegram" &&
     runtimeCapabilitiesLower.has("inlinebuttons");
   const skillsLines = skillsPrompt ? [skillsPrompt, ""] : [];
+  const skillsSection = skillsPrompt
+    ? [
+        "## Skills",
+        "Skills provide task-specific instructions. Use `read` to load the SKILL.md at the location listed for that skill.",
+        ...skillsLines,
+        "",
+      ]
+    : [];
 
   const lines = [
     "You are a personal assistant running inside Clawdbot.",
@@ -166,10 +174,7 @@ export function buildAgentSystemPrompt(params: {
     "TOOLS.md does not control tool availability; it is user guidance for how to use external tools.",
     "If a task is more complex or takes longer, spawn a sub-agent. It will do the work for you and ping you when it's done. You can always check up on it.",
     "",
-    "## Skills",
-    "Skills provide task-specific instructions. Use `read` to load the SKILL.md at the location listed for that skill.",
-    ...skillsLines,
-    "",
+    ...skillsSection,
     hasGateway ? "## Clawdbot Self-Update" : "",
     hasGateway
       ? [