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Phase 8 — Production Patterns: optimize, extend & ship

From "it works" to production. Phase 7 gave you the building blocks. This phase operationalizes them — make the loop cheap, give it new senses, and package it so a whole team can install it.

Executive summary

What this phase makes you able to do, and why it matters.

Once you can build the machinery (Phase 7), three production concerns decide whether it's actually usable at scale: cost, capability, and distribution. This phase covers the cheapest token optimization there is — prompt caching (reuse the stable prefix; reads cost ~0.1×) 1; how to give an agent eyes and hands to verify work no unit test can — computer use & browser agents, with the safety caveats that come with reading untrusted screens 2; and how to bundle your skills, hooks, and subagents into one installable, versioned plugin a team shares via a marketplace 3; and why you may not run agents you can't trace — run-level observability over OpenTelemetry, enforced as a precondition rather than a request 4. The throughline: a setup that works locally isn't done until it's cheap, capable, shippable, and traceable.

Prerequisite: Phase 7 — Advanced Patterns (the building blocks this phase operationalizes), plus Phase 2 (context as scarce) and Phase 3 (oracles).

Learning objectives

By the end of this phase you can: - Cut cost & latency with caching — structure prompts so the stable prefix is reused, and know what invalidates it. - Use a browser/UI agent as an oracle — drive visual self-verification for work with no unit test — safely. - Package & distribute a plugin — bundle skills + hooks + subagents into one versioned unit, shared via a marketplace. - Trace a session, not just a repo — capture prompts, tool calls, tokens, cost, and terminal state over OpenTelemetry, and gate work on tracing being configured.

The big idea (in one sentence)

A working agent setup isn't finished until it's cheap to run, able to see its own work, and easy for your team to install.

Lessons (one concept each)

# Lesson The one idea
1 Prompt & context caching Cache the stable prefix (tools→system→context); reads cost ~0.1×. Keep volatile content last.
2 Computer use & browser agents Eyes + hands: screenshot→act loop; a browser as a visual oracle — but untrusted screen = injection.
3 Plugins & marketplaces Bundle skills+hooks+subagents+MCP into one installable, versioned unit; share via a marketplace.
4 Observability before autonomy Repo telemetry says a rule fired; run telemetry (OTel) says why — trace before you walk away.

Phase diagram

flowchart LR
    M["the machinery from Phase 7<br/>(skills · hooks · MCP · security · subagents)"]
    M --> O["OPTIMIZE — cache the<br/>stable prefix (L1)"]
    M --> E["EXTEND — give it eyes<br/>& hands (L2)"]
    M --> SH["SHIP — bundle & share<br/>as a plugin (L3)"]
    M --> TR["TRACE — run telemetry<br/>as a precondition (L4)"]
    O --> P["agents that are cheap,<br/>capable, shareable, and traceable"]
    E --> P
    SH --> P
    TR --> P

Cheatsheet

Key terms

Term What people say What it actually means
Prompt caching "saving answers" Reusing the processed prefix (tools→system→context); reads cost ~0.1×, output unchanged 1.
Computer use "it can use my PC" A tool to screenshot + click/type a screen in a reason→act loop; untrusted screen content can inject it 2.
Visual oracle "screenshot testing" Using a browser snapshot as the correctness check for UI that has no unit-test assertion (Phase 3) 2.
Plugin "an extension" One installable unit bundling skills+commands+hooks+subagents+MCP/LSP; shared via a marketplace 3.
Marketplace "an app store" A git-hosted catalog of plugins — add it, then /plugin install name@marketplace 3.
Run telemetry "logging" A trace of the session itself — prompts, tool calls, spans, tokens, cost — distinct from repo-level lint/test signals 4.

Agent translation (same idea, different homes)

Concept Claude Code Codex Cursor
Prompt caching automatic automatic automatic
Browser control computer use · Playwright MCP computer-use tool · Playwright MCP Playwright MCP
Bundle & distribute plugins + marketplaces AGENTS.md in git .cursor/rules in git

→ Check your understanding

← Phase 7 — Advanced Patterns · Curriculum home · more topics → Roadmap

  1. Prompt caching — Anthropic ↩↩

  2. Computer use tool — Anthropic ↩↩↩

  3. Create plugins — Anthropic (Claude Code docs) ↩↩↩

  4. Monitoring — Anthropic (Claude Code docs) ↩↩