Lessons 85.1 through 85.3 produce trustworthy pieces. This lesson makes them compound. Most publications are piles: each post published, briefly promoted, abandoned. A library is different — pieces connected, reused, refreshed, each new artifact cheaper because earlier work exists. The mechanism is atomization with discipline.

Canonical, derivative, atomization

• A canonical piece is the authoritative treatment of one question: the full lesson with sources, reasoning, and evidence. One question, one canonical home — the same "one canonical home" principle the editorial standard demands for concepts.
• A derivative is a purposeful reworking for a different job: a checklist for doing, an email for notifying, a social explanation for discovering, an FAQ for answering, a workshop prompt for practicing, an update refreshing the original.
• Atomization is breaking the canonical piece into its reusable atoms — claims, steps, examples, diagrams, definitions — and reassembling them per job. Done well, each derivative serves a reader the original could not reach. Done badly, it is the same text reworded six times, which readers correctly experience as spam.
• Internal links connect derivatives back to the canonical piece and sideways to related ones, so readers (and search) find the full treatment.
• An inventory lists every asset with its status. Decay is the recognition that pieces rot: product facts age, examples stale, links die. An update cycle schedules re-verification per piece, fastest for time-sensitive facts.

The test of a legitimate derivative: it serves a distinct reader job with the minimum of the original, and links back rather than duplicating. A checklist a practitioner prints at their desk is legitimate. The lesson lightly rephrased is not. When planning, ask the job question first — "who needs this shape, and what will they do with it?" — and let the answer dictate which atoms to pull. Format follows the reader's task, never the team's convenience or the channel's hunger for volume.

One lesson, six lives

Take one strong source-linked lesson and give it six second lives:

1. Checklist — the procedural core as printable steps. 2. Email — the decision or announcement for subscribers, linking back. 3. Social explanation — one idea, self-contained, pointing to the full piece. 4. FAQ — the questions readers actually asked after publishing, answered briefly. 5. Workshop prompt — an exercise turning readers into doers. 6. Update — a scheduled refresh: corrected facts, new example, retired advice, logged in the record.

AI's production strengths (85.3) shine here: variants, summaries of provided material, metadata — all checkable against the canonical piece. Evidence discipline carries over unchanged: derivatives inherit the packet, add no new claims, and route new assertions back through review.

Maintain the system with a lightweight inventory habit: one row per asset, reviewed on the rhythm its decay rate earns. Stable conceptual lessons might be rechecked twice a year; pricing-adjacent or feature-dependent pieces quarterly or on every vendor announcement. Each review asks three questions: is everything still true, is anything important missing that readers now ask about, and do the derivatives still match the canonical piece? Log the answers with a date. Over a year, this habit converts the library from a pile of aging posts into a maintained asset whose average age of verification a reader — or a buyer — could actually trust.

Exercise: write your CONTENT-REUSE-MAP.md

Pick your strongest piece and map six derivatives:

# CONTENT-REUSE-MAP — [canonical piece title + URL]

1. Checklist — job: […] — atom used: […] — links back: [yes/sections]
2. Email — job: […] — atom used: […] — new claims: [none / listed + verified]
3. Social explanation — job: […] — atom used: […]
4. FAQ — job: […] — source: [reader questions from …]
5. Workshop prompt — job: […] — completion artifact: […]
6. Update — scheduled: [date] — decay risks: [facts/examples/links to recheck]

Inventory entry: status [current / needs-update / retired], owner […], next review […].

Finish line: six named derivatives, each with a distinct reader job and a link-back plan — plus an inventory entry with an owner and a next-review date.

Verify: for each derivative, cover the original and ask "could this stand alone for its job?" Then ask "does it send the reader home to the canonical piece?" Both answers must be yes.

Common failure mode: atomizing before a canonical piece exists — deriving six artifacts from a thin post multiplies thinness. The reuse map is a reward for depth, not a substitute for it. Its mirror image is the orphan derivative: a checklist or email published without its link back to the canonical piece, so improvements to the original never propagate and readers never find the full treatment. Every derivative ships with its return address attached, or it does not ship.

Check your understanding

1. What distinguishes a legitimate derivative from reworded duplication? 2. Why do derivatives inherit the evidence packet instead of adding fresh claims freely? 3. How does an update cycle convert decay from a threat into scheduled work?

Next, Lesson 85.5: close the loop — measure each piece on quality and business contribution, and let the monthly review decide what earns trust, what earns revenue, and what needs correction.