Purpose

Take a learner from surface understanding to genuine depth on a single concept. Assumes the learner has a working mental model and pushes into mechanism, failure modes, tradeoffs, and production implications. Exit condition: learner can reason about the concept in novel, constrained contexts.

Activation

• Learner asks to go deeper on a known concept. check-understanding confirms surface competence but weak mechanism knowledge. Interview prep or architectural decision needs depth.
• Skip if: beginner encountering concept for the first time → teach-concept. Needs immediate practical help → build-with-me/debug-teacher. Has a misconception → misconception-detector first.
• Routing: confirm current level with a quick probe before starting. Pair with challenge-generator at the end for advanced application.

Inputs

• Target concept, confirmed current understanding level, motivating context (interview/architecture/debugging), known gaps or questions.

Depth Ladder

Five rungs, each confirmed before ascending:

1. Surface — Definition and intuition → "State this in one sentence."
2. Mechanism — Step-by-step how it works → "Trace a concrete execution."
3. Tradeoffs — When it works vs. doesn't → "What would you choose instead, and why?"
4. Edge Cases — Boundaries and failures → "What breaks this?"
5. Production — Real-world tuning, monitoring, debugging → "How would you debug this at 3am?"

Workflow

1. Entry Check — Ask one question to confirm starting rung. Skip confirmed rungs; jump to the frontier.
2. Mechanism (Rung 2) — Walk through with a concrete worked trace. Require learner to narrate it back.
3. Tradeoffs (Rung 3) — Present a decision context. Elicit learner's reasoning before canonical analysis. Include one case where the naive choice is wrong.
4. Edge Cases (Rung 4) — Pose 2–3 edge case questions. Require learner to surface them first, then supplement. For each: symptom + fix.
5. Production (Rung 5) — Observability, performance under load, tuning knobs, known failure patterns. Ground in a realistic system. Ask: "If this broke at 3am, what's your investigation sequence?"
6. Exit Synthesis — Ask learner to produce a one-paragraph explanation for someone who just learned the basics.

Rules

• DO: confirm each rung before ascending — require exit question answers.
• DO: require learner narration at Rung 2, learner tradeoff reasoning at Rung 3, learner-surfaced edge cases at Rung 4.
• DO: use realistic scale at Rung 5 — not toy numbers.
• DON'T: re-teach confirmed surface level — skip to the frontier.
• DON'T: lecture all five rungs without learner participation at every rung.
• DON'T: end without learner producing an exit synthesis paragraph.

Output

Responses should contain: context (concept + starting rung + motivation), depth ladder progress, current rung exploration, checkpoint question, and exit synthesis prompt. Format naturally per rung.

Checklist

• Entry level confirmed; confirmed rungs skipped.
• Learner participation required at every rung.
• Rung 5 reached for intermediate+ learners.
• Exit synthesis produced by learner.