Pi native skills with disable-model-invocation cannot be invoked from BB

[IlyaM]

Summary

Pi-native skills declared with disable-model-invocation: true cannot be invoked through BB's Pi provider. The flag intentionally hides a skill from Pi's model-visible catalog, so an explicit invocation is the only supported way to load it; BB's command picker emits /name, but Pi requires /skill:name.

This differs from #2318: the affected skills are Pi-native skills discovered by Pi, not BB-managed skills injected through BB's skill system.

Versions and environment

• bb 0.42.1, run from source at dba32a469fd820ff6106715db0aaf6ed297d79a5
• Pi 0.85.0
• Linux (kernel 7.0.0); Node 22.22.1
• Pi provider, OpenAI Codex model

Steps to reproduce

1. Create or use a Pi-native skill in one of Pi's normal skill roots, such as ~/.pi/agent/skills/example/SKILL.md, with:

   ---
   name: example
   description: Test explicit skill invocation.
   disable-model-invocation: true
   ---

2. Start a BB thread with the Pi provider.

3. Select the example skill from BB's / command picker and send a prompt with any arguments.

4. Inspect the sent input with bb thread log <thread-id> --format json --all.

Expected vs actual

Expected: Selecting a Pi-native skill in BB invokes Pi's explicit skill command, loading the skill and passing the remaining text as its arguments. For a hidden skill, this is necessary because Pi intentionally excludes it from the model prompt.

Actual: BB serializes the selected command as /example and the Pi bridge forwards only that plain text. Pi's native command syntax is /skill:example; therefore the skill is not loaded. Because disable-model-invocation: true also hides it from the model-visible catalog, there is no fallback path: every affected skill is unavailable in BB Pi threads.

Evidence

• Pi documents disable-model-invocation: true as requiring the user to invoke /skill:name: https://github.com/earendil-works/pi/blob/main/packages/coding-agent/docs/skills.md#skill-commands
• BB's command catalog represents a skill with its bare name, rather than provider-native invocation syntax:

  bb/apps/server/src/services/threads/provider-command-typeahead.ts

  Lines 49 to 58 in dba32a4

  	function toSkillCommand(entry: ResolvedSkillCatalogEntry): ProviderCommand {
  	const { provenance, runtimeSource } = entry;
  	return {
  	name: runtimeSource.name,
  	source: "skill",
  	origin: provenance.kind === "project" ? "project" : "user",
  	description: runtimeSource.description,
  	argumentHint: null,
  	...(provenance.kind === "plugin" ? { pluginId: provenance.pluginId } : {}),
  	};

• The Pi bridge discards structured command-mention metadata while extracting input and forwards only text to Pi:

  bb/plugins/provider-pi/src/bridge/bridge.ts

  Lines 936 to 956 in dba32a4

  	function startPiPrompt(
  	threadSession: ThreadSession,
  	threadId: string,
  	text: string,
  	images: ImageContent[],
  	): Promise<void> {
  	const dispatch = threadSession.session.prompt(
  	text,
  	images.length > 0 ? images : undefined,
  	);
  	void dispatch.settled.then((outcome) => {
  	if (outcome === null) {
  	return;
  	}
  	reportPromptSettled({
  	...(outcome.error !== undefined ? { error: outcome.error } : {}),
  	sessionSerial: threadSession.sessionSerial,
  	threadId,
  	});
  	});
  	return dispatch.consumed;

  and

  bb/plugins/provider-pi/src/bridge/bridge.ts

  Lines 1164 to 1187 in dba32a4

  	function extractInput(input: TurnStartParams["input"]): ExtractedInput {
  	const chunks: string[] = [];
  	const images: ImageContent[] = [];
  	for (const item of input) {
  	if (!item || typeof item !== "object") continue;
  	const typed = item as {
  	type?: string;
  	text?: string;
  	path?: string;
  	mimeType?: string;
  	};
  	if (typed.type === "text" && typeof typed.text === "string") {
  	chunks.push(typed.text);
  	} else if (typed.type === "localImage" && typeof typed.path === "string") {
  	try {
  	const data = readFileSync(typed.path).toString("base64");
  	const mimeType = typed.mimeType ?? mimeTypeFromExtension(typed.path);
  	images.push({ type: "image", data, mimeType });
  	} catch {}
  	} else if (typed.type === "localFile" && typeof typed.path === "string") {
  	chunks.push(`[Attached file: ${typed.path}]`);
  	}
  	}
  	return { text: chunks.length > 0 ? chunks.join("\n") : undefined, images };

• I did not run a separate live reproduction during this diagnosis-only report; the report is based on the reported behavior and read-only source inspection. No public-safe investigation-thread link is available.

Suggested fix

Preserve a selected skill command as structured invocation data until the Pi adapter. For Pi-native skills, translate the selected skill into Pi's /skill:<name> syntax (with the remaining prompt text as arguments), rather than forwarding BB's provider-neutral /name display token. Add regression coverage for a Pi-native disable-model-invocation: true skill selected from the BB command picker.

What was ruled out

• Not Skill chip picked mid-message is serialized without trailing space and never reaches Claude Code as a skill #2318: that issue concerns BB-managed skill invocation and Claude Code behavior; this report concerns Pi-native skill commands and Pi's required /skill:name syntax.
• Not an ordinary model-selection failure: the affected skills are intentionally hidden from Pi's model catalog by their frontmatter.

Suggested priority and effort

High — this blocks all Pi-native skills that intentionally require explicit invocation, including safety-sensitive workflows. No in-BB workaround is known beyond removing the flag, which changes the skill's intended invocation policy.

AGENT GENERATED

[bb-slop-cop]

🚨 SLOP COP 🚨 · new-issue-autopilot

• Classification: Bug · Priority Medium · Effort Low
• Labels: providers, provider-pi, confirmed-repro
• Report: https://get-bb.github.io/reports/issues/3246.html
• Verdict: REPRODUCED · root-cause confidence: high
• Root cause: The Pi bridge forwarded display text without translating structured skill mentions into Pi's required native skill command.
• Reproduction label: confirmed-repro
• Pull request: Translate selected Pi skills to native commands #3249