Spec Driven Development — Chapter 03 Memory: 0b - Trilogy map: what lives in each volume

Stage: Complete
Next Step: None (frozen). Next chapter is Chapter 04.
Reading Span: PDF pages 20–22
Source Text: /library/Spec Driven Development/Chapter-03-Trilogy-map-what-lives-in-each-volume/Chapter-03-source-text.md (the chapter's own words; read instead of the PDF)
Full Record: /library/Spec Driven Development/Chapter-03-Trilogy-map-what-lives-in-each-volume/Chapter-03-chapter-notes.md (read only if needed)
Last Updated: 2026-10-01

Carried-in Context (from earlier chapters)

Ch1: Ködel's experience is offered as credibility, not proof; reader trusts him but wants to see the method.
Ch2: With fast AI code generation, a specification becomes the target for judging output; humans must judge, decide, answer. 70/30 framing is illustrative, not measured. Vibe-coding = vague prompting without a target.

Core Question: How does Ködel divide the work of building software with AI across his three books?
Core Thesis: Specification, architecture, and AI context are three connected concerns—what and why to build, where rules belong, and what information the model sees—while this volume is promised to remain usable on its own.
Key Concepts: SDD = what and why (verifiable target); FOCUS Architecture = where (rules located, dependencies point inward); Context Engineering = what the agent sees (selection and cost per call); stand-alone volume = cross-references explain the idea in place, with name and link.
Notable Arguments / Evidence Limits: Organizing map and a promise, not an empirical comparison. The stand-alone claim can be checked as cross-references appear.
Action Item: For one small feature, write three short lines: intended behavior and how to verify it; where its rule belongs in code; which specification and code excerpts an AI agent would need.

Pending Questions: None
Reader's Answers (paraphrase): Accurately recalled the three questions and order (what/why, where, what the agent sees/selection/cost). Proposed testing the author's practical claims against own experience. Follow-up: a cross-reference should include a small explanation of the concept it refers to.
Misconceptions / Feedback Given: Reader's “test it in my experience” is valuable but differs from the narrower stand-alone-volume promise; clarified the promise (name, link, summary in place).
Personal Threads: Reader has also started FOCUS Architecture and Context Engineering.

Check later cross-references to FOCUS / Context Engineering for in-place explanation (stand-alone promise).