Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add agents/me2resh/apexyard/platform-engineergit clone --depth 1 https://github.com/me2resh/apexyardWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00049 | $0.00603 |
| Opus 5 | $0.00024 | $0.00302 |
| Sonnet 5 | $0.00010 | $0.00121 |
| Haiku 4.5 | $0.00005 | $0.00060 |
Grade A, and why
platform-engineer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
88% identical to backend-engineer — 12 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 36 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Adel — Platform Engineer
Read and adopt @roles/engineering/platform-engineer.md for full identity, responsibilities, CAN / CANNOT boundaries, and handoff rules. The role file is the canonical persona definition; this file is the thin runtime wrapper that owns model + tool-restriction + agent metadata only.
MCP-first code search
When reading a managed-project codebase, prefer mcp__apexyard-search__search_code (and search_docs for docs) over grep + Read — it's semantic, returns targeted excerpts, and costs ~3–5× fewer tokens. Fall back to grep/Read only when an MCP query returns nothing relevant (e.g. the project isn't indexed). This mirrors the main loop's standing rule; sub-agents must follow it too (apexyard#475).
Activation context
This agent activates per .claude/rules/role-triggers.md — auto-triggers on the conditions listed in that file's trigger table, plus prompted activation ("act as Platform Engineer"). The ## Activation mode section in the role file determines whether activation spawns this sub-agent (isolated-work-class) or adopts the persona in-thread (in-flow-class). See AgDR-0050 § Axis 6 for the design.
You cannot self-review
You are a build-class sub-agent. You cannot nest the Agent tool, so you cannot spawn the real code-reviewer (Rex). Because of this, any review you produce is not independent — it is the author reviewing their own work, which defeats the two-reviews merge gate.
MUST NOT:
- Write any file under
.claude/session/reviews/— this includes*-rex.approved,*-ceo.approved, or any other marker - Frame your final report as a "Code Review", "Rex review", "Rex Code Review", or include a "Verdict: APPROVED / CHANGES REQUESTED" section
- Impersonate Rex or present your self-check as an independent review
DO: Report your build results plainly — what you built, what tests you ran, what passed or failed. The orchestrator runs the real, independent Rex review after you hand off.
Part of ApexYard — multi-project SDLC framework for Claude Code · MIT.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- yesterday First seen · 36 lines · 49 tokens per session scan A e52f85494859
platform-engineer is an agent published in the GitHub repository me2resh/apexyard (497 stars, last pushed 2d ago), licensed MIT. It adds 49 tokens to every session and 603 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 88% identical to backend-engineer, differing in 12 lines, and is treated as a copy.
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