Add APM manifest as alternate install path (additive to plugin)

[AlexDeMichieli]

What is APM?

APM (Agent Package Manager) is an open-source dependency manager for AI agent primitives — skills, prompts, instructions, hooks, agents, MCP servers. Think npm install but for agent configuration. One apm.yml describes everything an agent needs; apm install reproduces it deterministically on any machine, with content hashes pinned in apm.lock.yaml.

How it complements the plugin

Plugin install and APM install are additive, not competing — they operate at different layers:

• Plugin = the runtime bundle Copilot loads (agents/skills/hooks). Distributed via the Copilot marketplace and enabled centrally through the enterprise console + .github-private/.github/copilot/settings.json. Frictionless, GitHub-native, zero developer action.
• APM = the install/governance layer around those primitives. Files land in the consumer repo, pinned by hash, content-scanned, auditable in every PR.

The 4-layer defense-in-depth model

APM + hooks (from #33) together give you distinct checks at four moments in the agent lifecycle:

Moment	Layer	Check	Blocks
Author-time	APM producer	Schema validation	Malformed packages
Install-time	APM CLI	Content-integrity scan + policy	Hidden Unicode, prompt-injection payloads, disallowed sources, unpinned refs
PR-time	apm audit --ci	Drift / hash-mismatch check	Tampering with materialized primitives, hand-edits, sneaky diff
Runtime	Copilot hooks (#33)	preToolUse / postToolUse policy	Bad tool calls at execution (destructive writes, secret exfil, MCP alt-paths)

Plugin marketplace install gives you layer 4 only (once #33 lands). APM adds layers 1–3. That's the "regulated customers" pitch: defense in depth across the whole lifecycle, not just runtime.

Runtime hooks (PR #33) remain the enforcement point — APM never gates tool calls at execution. It stops bad code from reaching the agent; hooks stop the agent from doing bad things with the code it has.

When APM adds value

• Regulated customer (bank, gov, healthcare) — needs SBOM, lockfile provenance, tamper detection. apm lock export --format cyclonedx gives auditors a standard inventory of every prompt/skill an agent can see.
• Air-gapped / restricted network — the migration plugin files land in the consumer repo at install time, so no marketplace fetch is needed at runtime.
• Customer wants to customize skills — they fork, publish their own APM package, and their own apm-policy.yml restricts what other teams in their org can install on top of it.
• Multi-vendor AI stack — same apm.yml also configures Claude, Cursor, Codex, and others. Nothing else on the market does this today.
• Reproducibility — main moves; a pinned tag + content hash doesn't. Consumers don't get silently upgraded when we push to main.

Additional capabilities worth noting

• apm outdated — surfaces which pinned deps have newer versions available. Explicit updates, not automatic drift.
• Selective skill install — apm install .../plugin --skill jenkins-migration --skill actionlint cherry-picks; reduces attack surface.
• Enterprise policy (apm-policy.yml) — org-level rules (require_pinned_version, allowed_sources, require_explicit_includes) with tighten-only inheritance from enterprise → org → repo. Wired into apm audit --ci, so PRs that violate policy fail before merge.
• MCP-server trust prompts — transitive MCP servers require explicit consent; prevents "install skill X, get a hidden MCP server that reads your GitHub token" supply-chain attacks.
• Deployment ledger — records who deployed what and when, separate from the lockfile. Audit trail for change-control.

How to test

The APM CLI is client-side, so testing is a one-liner in any scratch repo. Verified end-to-end against feat/apm-manifest at commit 33d7d80:

# Install the APM CLI once
curl -sSL https://aka.ms/apm-unix | sh

# In a fresh test repo
mkdir /tmp/apm-migrator-test && cd /tmp/apm-migrator-test
git init
cat > apm.yml <<'YAML'
name: apm-migrator-test
version: 0.0.1
targets: [copilot]
dependencies:
  apm:
    - github/actions-migrations-via-copilot/plugin#feat/apm-manifest
YAML

apm install     # 9 agents + 11 skills materialized, apm.lock.yaml written
apm audit --ci  # 10/10 integrity checks pass on a fresh install

Note the /plugin suffix on the dependency spec — that's a virtual path pointing at the subdirectory where plugin.json lives. APM recognizes this as a Plugin collection package type (APM docs) and dissects plugin.json to install the agents and skills. Zero producer refactor required.

Once merged and a tag (e.g. v1.3.0) is cut, the dependency line becomes github/actions-migrations-via-copilot/plugin#v1.3.0.

Enforcement demos (verified locally)

Drift detection catches tampering. Modified a materialized skill file, apm audit --ci failed with:

content-integrity: 1 file(s) with hash drift
  hash-drift: .agents/skills/jenkins-migration/SKILL.md
  expected=fedf7085c7b9..., actual=6fe2322e9af7...
[x] 2 of 9 check(s) failed

Wire this into a .github/workflows/apm-audit.yml and tampered PRs never merge.

SBOM export works out of the box:

apm lock export --format cyclonedx  # or spdx

Produces an industry-standard bill of materials with the resolved commit SHA baked into the purl. Zero effort for procurement/compliance.

Scope

• apm.yml (new, minimal) — declares actions-migrator@1.2.0, targets: copilot. APM ignores this at install time (uses plugin/plugin.json via virtual path) but kept for future marketplace: block authoring.
• README.md — new Option C — Install via APM subsection alongside existing Options A/B, documents the /plugin virtual-path syntax.
• .gitignore — append APM-generated paths (apm_modules/, build/, .agents/).

No behavior change to the plugin runtime. Additive only. Zero file overlap with #33.

Deferred to follow-ups

• Commit apm.lock.yaml (needs apm install from a maintainer)
• .github/workflows/apm-audit.yml for apm audit --ci on every PR
• docs/enterprise/apm-policy-example.yml
• After feat: deterministic enforcement hooks for migration quality #33 merges, evaluate whether hooks should also ship as an APM primitive (they already work via plugin channel)

Refs

• APM: https://github.com/microsoft/apm
• Package types: https://microsoft.github.io/apm/reference/package-types/
• Reference producer PR: https://github.com/github/expert-services-agent-skill/pull/3
• Companion runtime-enforcement PR: feat: deterministic enforcement hooks for migration quality #33

[Copilot]

Pull request overview

Adds an experimental APM installation path alongside existing Copilot plugin options.

Changes:

• Adds an APM package manifest.
• Documents APM installation and governance benefits.
• Ignores APM-generated output.

Show a summary per file

File	Description
apm.yml	Defines APM package metadata and target.
README.md	Documents APM installation and comparison.
.gitignore	Excludes generated APM artifacts.

Review details

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• Files reviewed: 2/3 changed files
• Comments generated: 4
• Review effort level: Medium

[Copilot]

Review details

Comments suppressed due to low confidence (1)

README.md:116

• This pinned example resolves the existing v1.2.0 tag, whose commit predates and does not contain the new apm.yml. As a result, consumers copying this command cannot use the manifest or its includes declaration, so the documented APM install path is not reproducible from that release. Point this at the first release tag that actually contains the manifest (the repository already also has v1.3.0, which likewise predates it), or clearly use a temporary ref until that release is cut.

    - github/actions-migrations-via-copilot#v1.2.0

• Files reviewed: 2/3 changed files
• Comments generated: 0 new
• Review effort level: Medium

[Copilot]

Review details

Comments suppressed due to low confidence (1)

apm.yml:25

• This manifest is not installable as the repository-root package described in the PR test. APM only classifies an apm.yml package when it has a .apm/ source tree or non-empty dependencies; this repo has neither, and the actual plugin.json is under plugin/. As a result, github/actions-migrations-via-copilot#<ref> is classified as invalid, while the documented /plugin install bypasses this new manifest entirely. Move/expose the plugin primitives in an APM-recognized root layout (or otherwise make the root package resolve to plugin/) and verify the root-reference test.

includes: auto

• Files reviewed: 2/3 changed files
• Comments generated: 1
• Review effort level: Medium