feat(skills): add retrospective skill

src/skills/retrospect/SKILL.md

@@ -0,0 +1,44 @@
+---
+name: retrospect
+description: "Conduct a retrospective on a coding session."
+disable-model-invocation: true
+---
+
+The user has asked for a **retrospective**. You are suggesting improvements to the coding agent's **environment** to improve future runs.
+
+## Steps
+
+1. Read [`../agent-writing-guide/SKILL.md`](../agent-writing-guide/SKILL.md).
+
+2. Read the primary sources for the session the user specifies. This may mean searching through session logs on this machine. If the user doesn't specify a session, default to the current one.
+
+3. Look for candidates for improvement in these categories.
+
+- **Navigation**: how easy was it for the agent to find the right files? Are there hidden dependencies between files? Would a **navigation pointer** make it easier? _Use when_ the session took a long time to find a piece of information.
+- **Automated checks**: are there automated checks that could catch errors the agent made? Linting, typing, tests, filesystem linters? Read the repo's own check command first (its `package.json`/build-tool `lint`/`check` scripts, its CI workflow), so a check that already exists but sits unwired or silently broken is the finding, not a reinvention. A repo with no **guardrail** (no pre-commit hook and no CI job running its lint/typecheck/test command) is itself a finding: an un-linted repo is a standing missed opportunity, not a neutral default. _Use when_ the agent made a mistake an automated check could have caught, or the repo has no guardrail at all.
+- **Coding standards**: should the **reviewer agent** be given a new rule to enforce? Should an existing rule be removed or clarified? Classify the violation first: a **mechanical** one (a fixed syntactic pattern, a banned API, an import shape, a file-location rule) gets a deterministic check, full stop: a custom rule in the repo's own linter, a new pre-commit hook, or a new CI job, whichever the repo's language and existing guardrail make cheapest. Default to building the check over writing the rule. Reserve **review standards** for genuine **judgement calls** (cross-file consistency, "matches the surrounding style," anything no guardrail could ever substitute for). Before proposing a rule, identify the repository source that its review workflow loads. Keep the rule in that established source. _Use when_ the reviewer agent failed to catch a mistake.
+- **Global AGENTS.md**: are there any steering instructions that should be moved to review standards (or automated checks) instead? _Use when_ the AGENTS.md file is particularly large - in the repo OR the user's global scope.
+- **Tool economy**: did the agent make expensive tool calls that could be streamlined? Is there any custom tooling (CLI's, MCP's) that is particularly token-inefficient? _Use when_ the agent made an expensive tool call.
+- **No-ops**: look for instructions in steering files that don't modify the agent's behavior. _Use when_ the steering files are large and unwieldy.
+- **Information access**: look for opportunities to increase the agent's access to information. Teeing dev server logs, readonly access to third-party services. _Use when_ a crucial piece of information was not available to the agent.
+
+4. Present these candidates to the user, in order of severity.
+
+## Reference
+
+### Implementation vs Review
+
+Remember that all work goes through two stages: implementation and review. The implementation agent has the most **context pressure**. They are responsible for exploration, writing code, and debugging failures.
+
+The review agent has the least context pressure - it receives a diff, so no exploration needed. It often does not need to write code or debug.
+
+This means that the review agent should be responsible for imposing coding standards, not the implementation agent.
+
+### Files
+
+You have access to several files in the repo:
+
+- `AGENTS.md`: these files are pushed to the context window of any agent working in this repo. They should be used incredibly sparingly, usually only for **navigation pointers** to other files.
+- **Review standards**: these are the documented rules that the repository's review workflow loads. They can live in a standards file, a contribution guide, or scoped rule files. Find the existing source before proposing an addition.
+- Docs: use docs as references files, pointed to by other files. Look for existing docs before writing new ones.
+- Skills: use skills for docs (since their description goes into the agent's context window), or for user-invoked commands. Follow the advice in the `agent-writing-guide` skill.