blue/.blue/dialogues/2026-02-06T1839Z-rfc-0058-supersession-hybrid-relational-dynamodb-architecture/round-1.summary.md

Round 1 Summary — Judge's Synthesis

What Round 1 Answered

Q1: Does RFC 0053's trait boundary fully resolve the supersession question?

Partially. Croissant showed the trait resolves supersession conditionally — only if trait methods are bounded to O(1) partition reads. Strudel countered that 9 weeks of DynamoDB development will shape the trait with DynamoDB workarounds, silently making the decision. Galette grounded both arguments: the trait doesn't exist in code yet (30+ direct rusqlite::Connection calls), making this a debate about a foundation that hasn't been built.

Q2: Should the schema be redesigned around event streams?

Narrowed. Strudel scoped the claim from "redesign everything" to "redesign only the refs table." The other 13 entity types map cleanly to DynamoDB's partition model. Muffin argued event-sourcing strengthens the relational case (SQL views for materialization), while Cannoli countered that at actual volumes (~100 items per dialogue), full partition load + in-memory assembly makes the refs table's graph traversal trivially cheap.

Q3: What's the concrete rollback plan?

Resolved. Macaron resolved MACARON-T01: RFC 0053's single-active-backend factory pattern provides rollback — revert config to SQLite, no split-brain. Tartlet raised a deeper version: the encryption rollback is the hard problem, because migrating encrypted, hash-chained data between backends breaks the audit chain at the migration boundary.

Q4: Serverless or containerized?

Implicitly answered. Cannoli identified RFC 0058's architecture as implicitly serverless. Muffin conceded: if serverless, DynamoDB's operational model wins on deployment even as it loses on query expressiveness.

Q5: Can GSIs solve graph traversal?

No. Muffin and Eclair showed that GSIs solve single-hop adjacency but not transitive closure (4-hop verdict assembly). Cannoli's counter: at actual volumes, you don't need the GSI — load the whole partition and traverse in memory.

What Round 1 Surfaced

The Prerequisite Problem (Galette)

The most consequential R1 finding: RFC 0053's trait boundary is the mechanism every camp depends on, but it doesn't exist in code. alignment_db.rs has 30+ direct rusqlite::Connection call sites. The entire supersession debate is premature until this foundation is built — and building it costs the same regardless of which backend wins.

The Encryption Portability Gap (Tartlet)

The second critical finding: RFC 0058's AES-256-GCM envelope uses pk||sk in the AAD binding. If pk/sk are DynamoDB key structures, the encryption envelope is implicitly coupled to DynamoDB. No RFC specifies whether the envelope format is backend-portable.

The Denormalization Calcification Risk (Eclair, Strudel)

The trait hides which database answers the query, but it does not hide which database shaped the schema. DynamoDB-specific denormalized fields (verdict arrays, pre-computed ref chains) live in the domain model, not behind the trait. A future backend swap would require maintaining dead denormalization logic.

Emerging Resolution

The dialogue is converging toward a pragmatic sequence rather than an architectural winner:

1. Build the trait first — RFC 0053's DialogueStore trait must exist in code before any backend debate is load-bearing (Galette)
2. Design the trait from domain patterns, not backend workarounds — Strudel, Croissant
3. Add a trait governance gate — each new method must demonstrate O(1)-partition-read implementability (Croissant)
4. Specify encryption envelope portability — decouple AAD binding from DynamoDB key structure (Tartlet)
5. Ship DynamoDB behind the trait — RFC 0058 proceeds, but behind the abstraction (Macaron, Cannoli)
6. Redesign refs table specifically — per-entity adjacency lists vs separate refs table (Strudel)
7. Let production data drive any future swap — not speculation (Macaron, Cannoli)

Open Questions for Round 2

1. Can the denormalization cluster (3 tensions) be resolved by Strudel's refs-table-only redesign + Cannoli's in-memory assembly pattern?
2. What does the trait governance gate concretely look like? An RFC? An ADR? A review checklist?
3. Is encryption envelope portability a pre-condition for shipping RFC 0058, or can it be addressed in a follow-up RFC?
4. Does the prerequisite inversion (GALETTE R1-T01) change the conclusion or just the sequencing?