Junior To Senior

Junior to Senior

Assume the plan in front of you was written by a capable junior: fluent, confident, and trained on the past. Build a senior reviewer that is grounded in two things the junior was not — this codebase as it actually exists and the state of the art as it exists today — and let the senior tear the plan down and rebuild it.

This skill exists because agent-generated plans fail at two altitudes:

• Fog — the plan describes the high level fine ("add caching", "handle auth", "make it scalable") but never commits on the hard parts. No interfaces, no data shapes, no failure handling, no named libraries. An engineer reading it still has to make every real decision themselves.
• Tunnel — the plan dives into function signatures and file diffs but has no product vision. No statement of who this is for, what success means, what is out of scope, or why this approach beats the boring alternative. It optimizes a local detail while the shape of the feature is still wrong.

Both are altitude failures. The senior's job is to drag the plan to the right altitude and upgrade its substance past the model's training cutoff.

The cardinal rule

Every senior finding needs evidence. A claim about the codebase cites a file and line. A claim about best practice cites a fetched source — official docs, release notes, an RFC, a postmortem — with a date. If web research is unavailable, the finding is labeled [training-data, unverified] so stale knowledge is never laundered as current truth. A senior who argues from vibes is just a louder junior.

Phase 0: Capture the junior artifact

Identify exactly what is under review:

• A plan the agent just produced in this conversation (the default — including your own output from a moment ago).
• A pasted plan, design doc, RFC, or issue description.
• A planning document in the repo the user points at.

Freeze it. Quote or restate the artifact in full before reviewing so the review targets a fixed text, not a moving memory of it. If there is no artifact yet, say so and offer to either generate the junior draft first or review the user's existing idea — do not review thin air.

Phase 1: Construct the senior

The senior is not a tone of voice. It is a reviewer profile built from research done now. Skipping this phase and going straight to critique produces generic review slop.

1a. Extract the domains

List the 2-5 load-bearing technical domains the plan touches (e.g., "Postgres schema migration", "React server components", "OAuth token refresh", "vector search at 10M rows"). For each, write one sentence on what a staff-level engineer in that domain would refuse to let slide. This list drives all research that follows.

1b. Code research — what is true here

Investigate the repository before judging the plan against it:

• Existing conventions and architecture the plan must fit (or explicitly break, with justification).
• Actual versions in lockfiles/manifests — a plan recommending an API that the pinned version doesn't have is a blocker.
• Prior art: similar features already in the codebase, ADRs, migrations, test patterns.
• Real constraints the junior plan ignored: build system, deploy targets, performance budgets, existing data.

Use a subagent (e.g. Explore) for broad sweeps so the review context stays clean.

1c. Web research — what is true now

For each load-bearing decision in the plan, search for the current state of the art. The junior's knowledge ends at a training cutoff; the senior's must not. Prioritize primary sources (official docs, changelogs, release notes, maintainer posts) and check dates. You are looking for three kinds of delta:

• Deprecations — the plan's approach is now discouraged or removed.
• Supersessions — a newer pattern/library/API has clearly won since the cutoff.
• Hard-won lessons — published postmortems, benchmarks, or security advisories that change the tradeoff.

Query patterns, source-quality ranking, and when to stop are in references/research-playbook.md. If web access is unavailable, proceed on code research alone and mark every best-practice claim [training-data, unverified].

1d. Isolation

When the harness supports subagents, run the senior review in a context-isolated subagent that receives the frozen artifact and the research findings but not the reasoning that produced the junior plan. Self-review in the same context anchors on its own justifications; isolation is what makes the review adversarial rather than confirmatory.