[BUG] apm.lock.yaml still non-deterministic when MCP dependencies are present

[marclefrancois]

Describe the bug

Follow-up to #450 — the generated_at timestamp rewrite was fixed for regular APM dependencies, but the lockfile still changes on every apm install when MCP dependencies are declared in apm.yml. The only diff is the generated_at field, meaning the actual resolved state hasn't changed.

To Reproduce

1. Add an MCP dependency to apm.yml:

mcp:
    - name: atlassian
      registry: false
      transport: http
      url: https://mcp.atlassian.com/v1/mcp

2. Run apm install and commit apm.lock.yaml
3. Run apm install again without changing apm.yml
4. Run git diff apm.lock.yaml

  -generated_at: '2026-05-28T15:16:00.000000+00:00'
  +generated_at: '2026-05-28T15:18:00.000000+00:00'

Only the timestamp changes — no dependency content is different.

Expected behavior

apm install should be fully idempotent: if neither apm.yml nor any resolved dependency has changed, apm.lock.yaml must not be modified. This should hold regardless of dependency type (APM packages, MCP servers, etc.).

Environment

• OS: macOS
• Python Version: 3.12
• APM Version: 0.8.5

Additional context

The original fix for #450 likely only addressed the APM dependency resolution path. The MCP dependency resolution appears to follow a separate code path that still unconditionally rewrites generated_at. The fix should apply the same determinism logic to MCP nodes.

See my comments on #450:

• [BUG] apm.lock.yaml changes on every apm install due to generated_at timestamp #450 (comment)
• [BUG] apm.lock.yaml changes on every apm install due to generated_at timestamp #450 (comment)

[github-actions]

Triage decision

accept

Proposed labels

theme/governance
area/lockfile
type/bug
status/accepted
priority/high

Milestone

0.14.0

Suggested next action

Apply the same generated_at determinism gate from the #450 fix to the MCP dependency resolution code path so that apm install does not rewrite apm.lock.yaml when the MCP resolved state is unchanged.

Suggested issue comment

Thanks for the follow-up to #450 and for the linked comments that pinpoint the MCP code path -- this makes the fix very easy to scope.

The root cause is confirmed: the `generated_at` determinism gate applied in #450 covers the APM dependency resolution path but not the MCP node writer. Every `apm install` with MCP dependencies unconditionally rewrites `generated_at`, causing spurious lockfile diffs in CI.

This is accepted with priority/high on 0.14.0. The fix is to apply the same "has the resolved state actually changed?" check to the MCP lock node writer before updating `generated_at`. The existing APM dep path is the reference implementation.

Would you like to open a PR? If so, the MCP lock node writer in the install pipeline is the starting point.

Per-lens notes (collapsed)

DevX UX Expert -- User-Need Reviewer

Idempotent installs are a fundamental promise for a package manager: if nothing has changed, nothing should change. The diff showing only the generated_at timestamp change confirms the diagnosis. This breaks CI determinism for any team that commits apm.lock.yaml and checks for unexpected diffs. High priority.

Supply Chain Security Expert -- Risk-Surface Reviewer

Touches the lockfile (area/lockfile). Non-deterministic lockfiles undermine the audit trail: you cannot tell from git diff whether a lockfile change represents a real dependency update or just a timestamp rewrite. This is a governance surface -- the lockfile is the authoritative record of resolved state. theme/governance applies.

OSS Growth Hacker -- Contributor-Tone Reviewer

marclefrancois is NONE association, with a precise bug report and a pinpointed root cause. The reply should validate the diagnosis immediately, confirm the scope of the fix, and invite a PR contribution.

Python Architect -- Architecture Reviewer

The fix is well-scoped: locate the MCP lock node writer in the install pipeline, apply the same "has resolved state changed?" gate that the #450 fix applied to the APM dep path, and update generated_at only when the gate is true. This is a single code path change, no new module, no new contract. Status: accept.

Doc Writer -- Documentation Reviewer

Not activated -- this is a bug fix with no new user-facing surface; no docs change needed beyond a CHANGELOG entry.

APM CEO -- Triage Arbiter

Clear bug fix accept. The diagnosis is precise (MCP code path missing the #450 determinism gate), the fix is scoped to one code path, and the impact (broken CI determinism) is high. Priority/high, milestone 0.14.0, theme/governance (lockfile integrity is a governance surface).

{
  "decision": "accept",
  "decision_detail": "",
  "theme": "theme/governance",
  "areas": ["area/lockfile"],
  "type": "type/bug",
  "status": "status/accepted",
  "priority": "priority/high",
  "preserved_labels": [],
  "milestone": "0.14.0",
  "next_action": "Apply the same generated_at determinism gate from the #450 fix to the MCP dependency resolution code path.",
  "comment_markdown": "Confirmed: generated_at determinism gate from #450 covers the APM dep path but not the MCP node writer. Accepted with priority/high on 0.14.0. Fix: apply the same resolved-state-change check to the MCP lock node writer before updating generated_at. Would you like to open a PR?"
}

---

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