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fix(skill): dedupe skills with identical SKILL.md content #890

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fix(skill): dedupe skills with identical SKILL.md content #890

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c17ae49
fix(skill): dedupe skills with identical SKILL.md content
sailist Jun 18, 2026
30d87e2
chore: add changeset for duplicate skill dedupe fix
sailist Jun 18, 2026
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5 changes: 5 additions & 0 deletions .changeset/dedupe-identical-skills.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
"@moonshot-ai/kimi-code": patch
---

Fix duplicate skills appearing when a sub-skill is also shipped as a flattened copy with identical content.
21 changes: 21 additions & 0 deletions packages/agent-core/src/skill/scanner.ts
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Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
import { createHash } from 'node:crypto';
import { promises as fs } from 'node:fs';
import path from 'pathe';

Expand Down Expand Up @@ -139,6 +140,7 @@ export async function discoverSkills(
const warn = options.onWarning ?? (() => {});
const skip = options.onSkippedByPolicy ?? (() => {});
const byName = new Map<string, SkillDefinition>();
const byContent = new Map<string, SkillDefinition>();

async function walkSkillDir(
dirPath: string,
Expand Down Expand Up @@ -177,6 +179,7 @@ export async function discoverSkills(
const skill = await parseAndRegister({
parse,
byName,
byContent,
skillMdPath: path.join(dirPath, entry, 'SKILL.md'),
skillDirName: entry,
root,
Expand All @@ -202,6 +205,7 @@ export async function discoverSkills(
await parseAndRegister({
parse,
byName,
byContent,
skillMdPath: rootSkillMd,
skillDirName: path.basename(dirPath),
root,
Expand All @@ -227,6 +231,7 @@ export async function discoverSkills(
await parseAndRegister({
parse,
byName,
byContent,
skillMdPath,
skillDirName: skillName,
root,
Expand Down Expand Up @@ -362,6 +367,7 @@ async function pushProvidedRoot(
async function parseAndRegister(input: {
readonly parse: NonNullable<DiscoverSkillsOptions['parse']>;
readonly byName: Map<string, SkillDefinition>;
readonly byContent: Map<string, SkillDefinition>;
readonly skillMdPath: string;
readonly skillDirName: string;
readonly root: SkillRoot;
Expand All @@ -371,6 +377,9 @@ async function parseAndRegister(input: {
readonly subSkillParentName?: string;
}): Promise<SkillDefinition | undefined> {
try {
const raw = await fs.readFile(input.skillMdPath, 'utf8');
const contentHash = hashSkillContent(raw);

const parsed = await input.parse({
skillMdPath: input.skillMdPath,
skillDirName: input.skillDirName,
Expand All @@ -392,6 +401,14 @@ async function parseAndRegister(input: {
...skill,
plugin: input.root.plugin,
};
const existing = input.byContent.get(contentHash);
if (existing !== undefined) {
const preferCurrent =
discovered.metadata.isSubSkill === true && existing.metadata.isSubSkill !== true;
if (!preferCurrent) return undefined;
Comment on lines +404 to +408

@chatgpt-codex-connector chatgpt-codex-connector Bot Jun 18, 2026

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P2 Badge Do not dedupe every identical content hash

When two distinct skills happen to have byte-identical markdown, this returns before onDiscoveredSkill and before adding the second name. That drops legitimate cases such as foo.md and bar.md with the same body but different filename-derived names, and it also prevents SessionSkillRegistry.loadRoots from indexing the second plugin's copy for getPluginSkill when two enabled plugins vendor the same startup SKILL.md; those are not flattened sub-skill duplicates and should remain addressable.

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input.byName.delete(normalizeSkillName(existing.name));
}
input.byContent.set(contentHash, discovered);
input.onDiscoveredSkill?.(discovered);
const key = normalizeSkillName(discovered.name);
if (!input.byName.has(key)) {
Expand All @@ -414,6 +431,10 @@ async function parseAndRegister(input: {
}
}

function hashSkillContent(content: string): string {
return createHash('sha256').update(content).digest('hex');
}

function qualifySubSkillName(parentName: string, skillName: string): string {
if (skillName === parentName || skillName.startsWith(`${parentName}.`)) return skillName;
return `${parentName}.${skillName}`;
Expand Down
28 changes: 28 additions & 0 deletions packages/agent-core/test/skill/scanner.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -368,6 +368,34 @@ describe('discoverSkills shape and ordering', () => {
expect(skills.find((s) => s.name === 'outer.inner')?.metadata.isSubSkill).toBe(true);
});

it('dedupes identical SKILL.md files discovered via flattened subskill copies', async () => {
const { repoDir } = await makeWorkspace();
const root = path.join(repoDir, '.kimi-code', 'skills');
const childContent = [
'---',
'name: legacy-child',
'description: Nested skill',
'---',
'',
'Child body.',
];
await writeSkill(root, path.join('outer', 'SKILL.md'), [
'---',
'name: outer',
'description: Parent skill',
'has-sub-skill: true',
'---',
'',
'Outer body.',
]);
await writeSkill(root, path.join('outer', 'child', 'SKILL.md'), childContent);
await writeSkill(root, path.join('outer__child', 'SKILL.md'), childContent);

const skills = await discoverSkills({ roots: [{ path: root, source: 'user' }] });

expect(skills.map((s) => s.name)).toEqual(['outer', 'outer.legacy-child']);
});

it('does not discover nested SKILL.md files when the parent bundle disables sub-skills', async () => {
const { repoDir } = await makeWorkspace();
const root = path.join(repoDir, '.kimi-code', 'skills');
Expand Down
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