@struktoai/mirage-core/dist/core/github/events.js

A Unified Virtual Filesystem For AI Agents

// ========= Copyright 2026 @ Strukto.AI All Rights Reserved. =========
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
// ========= Copyright 2026 @ Strukto.AI All Rights Reserved. =========
import { FileChangeKind } from "../../types.js";
import { eventAt, field, textField } from "../../events/payload.js";
// The most commits GitHub lists in one push delivery; a push at the cap may
// have lost some, so its paths are not the whole change.
const COMMIT_CAP = 2048;
// The lists each pushed commit carries, and the change each one is.
const ACTIONS = ['added', 'removed', 'modified'];
/**
 * Map one GitHub `push` webhook delivery onto mount paths.
 *
 * The consumer owns the receiver (a repository webhook for `push`) and passes
 * the event name from the `X-GitHub-Event` header with the JSON body. Nothing
 * here runs a loop. A mount reads one ref of one repository, so only a push to
 * that ref maps to anything.
 *
 * Each pushed commit lists the paths it added, removed and modified, so a
 * path's change is its first and last action across the push: one added and
 * then removed within the push never existed outside it and maps to nothing.
 * A forced push, a branch created or deleted, and a push at GitHub's commit cap
 * do not say what changed between the old head and the new one, so the whole
 * mount is UNKNOWN. Each event evicts the root listing above it, so the next
 * read fetches the new head's tree.
 *
 * Mirrors Python `GitHubEventHook` (`core/github/events.py`).
 */
export class GitHubEventHook {
    accessor;
    constructor(accessor) {
        this.accessor = accessor;
    }
    toEvents(root, eventName, payload) {
        return Promise.resolve(this.map(root, eventName, payload));
    }
    map(root, eventName, payload) {
        if (eventName !== 'push')
            return [];
        const { owner, repo, ref } = this.accessor;
        const repository = field(payload, 'repository');
        const name = textField(repository, 'full_name') ?? '';
        if (name.toLowerCase() !== `${owner}/${repo}`.toLowerCase())
            return [];
        const pushed = textField(payload, 'ref');
        if (pushed !== `refs/heads/${ref}` && pushed !== `refs/tags/${ref}`)
            return [];
        const commits = field(payload, 'commits');
        if (['forced', 'created', 'deleted'].some((flag) => field(payload, flag) === true) ||
            !Array.isArray(commits) ||
            commits.length >= COMMIT_CAP) {
            return [eventAt(root, '', FileChangeKind.UNKNOWN)];
        }
        const first = new Map();
        const last = new Map();
        for (const commit of commits) {
            for (const action of ACTIONS) {
                const paths = field(commit, action);
                for (const path of Array.isArray(paths) ? paths : []) {
                    if (typeof path !== 'string')
                        continue;
                    if (!first.has(path))
                        first.set(path, action);
                    last.set(path, action);
                }
            }
        }
        const events = [];
        for (const [path, action] of first) {
            const final = last.get(path);
            if (action === 'added' && final === 'removed')
                continue;
            const kind = action === 'added'
                ? FileChangeKind.CREATE
                : final === 'removed'
                    ? FileChangeKind.DELETE
                    : FileChangeKind.UPDATE;
            events.push(eventAt(root, path, kind));
        }
        return events;
    }
}
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