Project 6 — Complete AI Solutions Architecture Case Study

The complete AI solutions architecture case study is the capstone of the capstones — one end-to-end design, documented (L386) — the case study (the requirements L359 → the ADRs L361 → the architecture L379 → the projects L381–385, L386), the documentation (the L380 toolkit L380: the ADRs L361, the diagrams L380, the cost models L368, the decision rule L380, L386), and the defense (the interview's L386: the why L367 at each L386) — the architect's (L380) proof (L386).

The one-sentence interview answer: "The case study is the capstone of the capstones (L386). The case study (L386): the end-to-end design (L386) — the requirements (L359): the brief (L359); the ADRs (L361): the model (L365), the RAG (L349), the cloud (L366); the architecture (L379): the front door (L267), the engine room (L270), the data (L268); and the projects (L381–385): the RAG SaaS (L381), the guarded agent (L382), the automation (L383), the SaaS (L384), and the enterprise (L385). The documentation (L380): the L380 toolkit (L380) — the ADRs (L361), the diagrams (L380), the cost models (L368), and the decision rule (L380). The defense (L386): the interview's (L386) — the why (L367) at each (L386): the trade-offs (L367) named (L386), the evals (L341) shared (L386). The AI shape (L173): the architect (L386) — the end-to-end design (L386), documented (L380), and defended (L386) — the M30 milestone (L386), the final (L386) of the curriculum (L386)."

Think of the case study as the master builder's final project. The final project (the case study, L386) demonstrates the whole craft (L386): the client's brief (the requirements, L359); the signed contracts (the ADRs, L361); the blueprints (the diagrams, L380); the costed ledgers (the cost models, L368); and the built structures (the projects, L381–385) — the RAG library (L381), the guarded bank (L382), the automation factory (L383), the office tower (L384), and the private campus (L385). The master builder (L386) presents (L386): the brief (L359), the decisions (L361), and the builds (L381) — the why (L367) at each (L386). The portfolio (L103) is complete (L386) — the capstone of the capstones (L386).

   the final project (the case study, L386)
   ┌────────────────────────────────────────────────────────┐
   │ the brief (L359) · the contracts (L361) · the          │
   │ blueprints (L380) · the ledgers (L368)                 │
   │ the builds (L381–385) — the library (L381), the bank   │
   │ (L382), the factory (L383), the tower (L384), the      │
   │ campus (L385)                                          │
   └────────────────────────────────────────────────────────┘

The mental model is the final project: the brief, the contracts, and the builds (L386).

   1 · THE REQUIREMENTS (L359) → the brief (L359)
   2 · THE DECISIONS (L361) → the ADRs (L361) with the trade-offs (L367)
   3 · THE ARCHITECTURE (L379) → the floor plan (L260)
   4 · THE PROJECTS (L381–385) → the five builds (L386)
   5 · THE DOCUMENTATION (L380) → the toolkit (L380)
   6 · THE DEFENSE (L386) → the why at each (L367)

The flow is the case study: requirements → decisions → architecture → projects → documentation → defense (L386).

• The case study (L386). The end-to-end design (L386): the requirements (L359), the ADRs (L361), the architecture (L379), the projects (L381–385).
• The documentation (L380). The L380 toolkit (L380): the ADRs (L361), the diagrams (L380), the cost models (L368), the decision rule (L380).
• The defense (L386). The interview's (L386): the why (L367) at each (L386).
• The arc (L386). The curriculum's (L386): the L135 start (L135) to the L386 capstone (L386).

• The portfolio (L103). The case study (L386) — the portfolio's (L103) centerpiece (L386).
• An interview (L386). The defense (L386) — the why at each (L367).
• A design review (L386). The documentation (L380) — the ADRs (L361) and the diagrams (L380).
• A board presentation (L360). The cost models (L368) — the board's (L360) number (L368).
• The curriculum (L386). The capstone (L386) — the final (L386) of the roadmap (L386).

The through-line: the capstone is the curriculum's — the end-to-end design, documented and defended (L386).

Say it in four moves:

1. The case study. "The requirements (L359) → the ADRs (L361) → the architecture (L379) → the projects (L381–385)."
2. The documentation. "The L380 toolkit (L380) — the ADRs, the diagrams, the cost models, the decision rule (L380)."
3. The defense. "The why (L367) at each (L386)."
4. The arc. "The L135 start (L135) to the L386 capstone (L386)."

• The arc is the curriculum's (L386). The L135 start (L135) to the L386 capstone (L386) — the modules (L386) assembled (L386).
• The documentation is the toolkit's (L380). The ADRs (L361), the diagrams (L380), the cost models (L368), and the decision rule (L380) — the L380 bag (L380), in the case (L386).
• The defense is the why's (L367). The trade-offs (L367) named (L367) — the evals (L341) shared (L360) — the interview's (L386) proof (L386).
• The projects are the proofs (L381–385). The RAG (L381), the agent (L382), the automation (L383), the SaaS (L384), the enterprise (L385) — the L103 portfolio (L103), filled (L386).
• The milestone is the final (L386). M30 (L386) — the last (L386) of the curriculum (L386) — the architect (L380), claimed (L386).

• The project-only (L386). The builds (L381–385) without the documentation (L380) — the toolkit (L380) missing (L386).
• The decision-less (L361). The architecture (L379) without the ADRs (L361) — the why (L367) lost (L386).
• The defense-less (L386). The design (L386) without the why (L367) — the interview (L386) fails (L386).
• The cost-less (L368). The case (L386) without the models (L368) — the board (L360) rejects (L386).
• The arc-less (L386). The pieces (L386) without the arc (L386) — the L135 to the L386 (L386) un-assembled (L386).

• Assemble the arc (L386) — the requirements (L359) to the projects (L381–385).
• Document the toolkit (L380) — the ADRs (L361), the diagrams (L380), the cost models (L368).
• Name the trade-offs (L367) — at each decision (L361).
• Share the evals (L341) — the quality (L341) evidenced (L360).
• Defend the why (L386) — the interview's (L386) proof (L386).

Q: Walk me through the case study.

A: The capstone of the capstones (L386). The case study — the requirements (L359), the ADRs (L361), the architecture (L379), and the projects (L381–385). The documentation — the L380 toolkit (L380). And the defense — the why at each (L367).

Q: What's in the documentation?

A: The L380 toolkit (L380): the ADRs (L361) — the decisions (L361) with the trade-offs (L367); the diagrams (L380) — the floor plan (L260) and the flows (L380); the cost models (L368) — the board's (L360) number (L368); and the decision rule (L380) — the spine (L380). The bag (L380), in the case (L386).

Q: How do the projects fit?

A: The proofs (L381–385): the RAG SaaS (L381) — the L349 platform (L349); the guarded agent (L382) — the L216 loop (L216); the automation (L383) — the L356 product (L356); the SaaS (L384) — the L357 shape (L357); and the enterprise (L385) — the L380 enterprise (L380). The L103 portfolio (L103), filled (L386).

Q: What's the arc?

A: The curriculum's (L386): the L135 start (L135) — the foundations (L135) — to the L386 capstone (L386) — the modules (L386) assembled (L386): the app (L158), the RAG (L174), the agents (L198), the automation (L217), the backend (L233), the cloud (L261), the pipeline (L288), the security (L308), the observability (L328), the design (L347), and the enterprise (L359) — the end-to-end design (L386), documented (L380), and defended (L386). The architect (L380), claimed (L386).

• What's in the documentation (L380)?
• How do the projects fit (L381–385)?
• What's the arc (L386)?
• How do you defend it (L386)?
• What's the milestone (L386)?

The senior read: the case study assembles the projects — the capstone of the capstones (L386).

// The case study (L386) — the end-to-end design (L386).
// 1 · THE ARC (L386) — the curriculum's (L386).
const arc = {
  foundations:  'L135-L157',      // the model decision (L148)
  app:          'L158-L173',      // the AI app (L173)
  rag:          'L174-L197',      // the knowledge (L197)
  agents:       'L198-L216',      // the loop (L216)
  automation:   'L217-L232',      // the workflows (L230)
  backend:      'L233-L260',      // the floor plan (L260)
  cloud:        'L261-L287',      // the deployment (L287)
  pipeline:     'L288-L307',      // the shipping (L307)
  security:     'L308-L327',      // the stack (L325)
  observability:'L328-L346',      // the standard (L346)
  design:       'L347-L358',      // the protocol (L347)
  enterprise:   'L359-L380',      // the toolkit (L380)
};

// 2 · THE PROJECTS (L381–385) — the proofs (L386).
const projects = [
  { id: 'P1', build: 'rag-saas',         proof: 'L349' },   // L381
  { id: 'P2', build: 'guarded-agent',    proof: 'L216' },   // L382
  { id: 'P3', build: 'automation',       proof: 'L356' },   // L383
  { id: 'P4', build: 'multi-tenant-saas', proof: 'L357' },  // L384
  { id: 'P5', build: 'enterprise-ai',    proof: 'L380' },   // L385
];

// 3 · THE DOCUMENTATION (L380) — the toolkit (L386).
const documentation = {
  adrs:       'the decisions (L361)',        // L361
  diagrams:   'the floor plan (L260)',       // L380
  costModels: 'the board's number (L368)',   // L368
  decisionRule: 'the spine (L380)',          // L380
};

// 4 · THE DEFENSE (L386) — the why at each (L367).
//   "the RAG (L349) for the freshness (L335) at the latency (L333)"

What the reader must SEE — the case, assembled:

  the L135 → L386 arc       → the curriculum (L386)
  the five projects         → the proofs (L381–385)
  the ADRs + the diagrams   → the toolkit (L380)
  the why at each           → the defense (L367)

  The end-to-end design, documented and defended (L386).

• The case is the interview's speed (L386). The assembled arc (L386) — the defense (L386) structured (L386).
• The documentation is the review's (L380). The ADRs (L361) and the diagrams (L380) — the review (L386) fast (L386).
• The cost models are the board's (L368). The number (L368) — the sign-off (L360) fast (L386).
• The portfolio is the proof's (L103). The projects (L381–385) — the L103 portfolio (L103), filled (L386).

• The complete case study = the capstone of the capstones (L386): the case study, the documentation, the defense.
• The case study: the requirements (L359) → the ADRs (L361) → the architecture (L379) → the projects (L381–385).
• The documentation: the L380 toolkit (L380).
• The defense: the why (L367) at each (L386).
• The arc: the L135 start (L135) to the L386 capstone (L386).

THE COMPLETE AI SOLUTIONS ARCHITECTURE CASE STUDY = the capstone
of the capstones

THE CASE STUDY (L386)
  the requirements (L359) → the ADRs (L361) → the architecture
  (L379) → the projects (L381–385)
  the RAG SaaS (L381) · the agent (L382) · the automation (L383)
  the SaaS (L384) · the enterprise (L385)

THE DOCUMENTATION (L380)
  the ADRs (L361) · the diagrams (L380) · the cost models (L368)
  the decision rule (L380) — the toolkit (L380)

THE DEFENSE (L386)
  the why (L367) at each (L386) — the trade-offs (L367) named (L367)
  the evals (L341) shared (L360) — the interview's (L386) proof (L386)

THE ARC (L386)
  the L135 start (L135) → the L386 capstone (L386)
  the twelve modules (L386) assembled (L386)

THE MILESTONE (M30)
  the final (L386) of the curriculum (L386)
  the architect (L380), claimed (L386)

INTERVIEW, 4 MOVES
  1 case    "the requirements to the projects (L386)"
  2 documentation "the toolkit (L380)"
  3 defense "the why at each (L367)"
  4 arc     "the L135 to the L386 (L386)"

That was the last lesson of the Capstone Projects module — and the capstone of the entire curriculum. L135–L385 gave you the knowledge and the builds; this lesson gave you the case study: one end-to-end design, documented with the toolkit (L380), and defended with the why (L367). When you can assemble the arc (L386), document the decisions (L361), cost the models (L368), and defend the trade-offs (L367) — you have claimed Milestone M30, the final milestone of the curriculum.

The portfolio (L103) is now complete: the RAG SaaS (L381), the guarded agent (L382), the automation platform (L383), the multi-tenant SaaS (L384), the enterprise assistant (L385), and the complete case study (L386). The interview (L104) awaits — and the mock-interview playbook (L104) is the next page of the original roadmap. The Solutions Architect is built; the proof is in the portfolio; and the room is yours to walk.