ai_synth/audits/2026-03-27/backend-rust.md

Backend Rust Audit Report (Partial)

Scope and limitations

• Audited backend docs + code paths in:
  • handlers/, services/, db/, models/, migrations, representative tests
• Limitation:
  • Full backend test execution could not be completed due persistent Cargo artifact lock after interruption.

Clarification Questions

1. Is "LLM vs HTML source-link extraction mode" still a product requirement, or intentionally removed?
   • Docs still mention configurability (functional_specs.md:140)
   • Related settings were removed in migrations (20260326000026_remove_use_llm_for_source_links.sql, 20260325000018_drop_deprecated_settings.sql)
2. What are canonical theme defaults: docs/DB (max_items=4, summary_length=3) or handler (5, 2)?

Assumptions

• Docs are source of truth unless explicitly superseded by migration intent.
• Multi-theme source scoping is mandatory.

Prioritized Findings

P0

• Theme-scoped source import/export contract is broken.
  • Evidence: /Users/oabrivard/Projects/rust/ai_synth/backend/src/handlers/sources.rs:111, /Users/oabrivard/Projects/rust/ai_synth/backend/src/handlers/sources.rs:154, /Users/oabrivard/Projects/rust/ai_synth/backend/src/handlers/sources.rs:234, /Users/oabrivard/Projects/rust/ai_synth/backend/src/services/synthesis.rs:120, /Users/oabrivard/Projects/rust/ai_synth/backend/src/handlers/sources.rs:249
  • Spec refs: /Users/oabrivard/Projects/rust/ai_synth/docs/requirements.md:19, /Users/oabrivard/Projects/rust/ai_synth/docs/functional_specs.md:35
  • Direction: make import/export strictly theme-aware.

P1

• Theme update endpoint lacks validation; invalid settings can persist.

  • Evidence: /Users/oabrivard/Projects/rust/ai_synth/backend/src/models/theme.rs:77, /Users/oabrivard/Projects/rust/ai_synth/backend/src/handlers/themes.rs:72, /Users/oabrivard/Projects/rust/ai_synth/backend/src/db/themes.rs:72
  • Direction: add UpdateThemeRequest::validate() and enforce in handler.

• Source create/import path does not verify theme ownership.

  • Evidence: /Users/oabrivard/Projects/rust/ai_synth/backend/src/handlers/sources.rs:72, /Users/oabrivard/Projects/rust/ai_synth/backend/src/db/sources.rs:55
  • Direction: enforce theme_id ownership check before insert/update.

• Theme creation contract drifts from documented behavior/defaults.

  • Evidence: /Users/oabrivard/Projects/rust/ai_synth/backend/src/models/theme.rs:43, /Users/oabrivard/Projects/rust/ai_synth/backend/src/models/theme.rs:47, /Users/oabrivard/Projects/rust/ai_synth/docs/functional_specs.md:90, /Users/oabrivard/Projects/rust/ai_synth/backend/src/handlers/themes.rs:56, /Users/oabrivard/Projects/rust/ai_synth/docs/functional_specs.md:185
  • Direction: align create validation + defaults with agreed product contract.

P2

• Core synthesis orchestration is monolithic and high-risk to change.

  • Evidence: /Users/oabrivard/Projects/rust/ai_synth/backend/src/services/synthesis.rs:85, /Users/oabrivard/Projects/rust/ai_synth/backend/src/services/synthesis.rs:152, /Users/oabrivard/Projects/rust/ai_synth/backend/src/services/synthesis.rs:357, /Users/oabrivard/Projects/rust/ai_synth/backend/src/services/synthesis.rs:542
  • Direction: split into composable phase modules.

• Scheduler reliability path is under-tested.

  • Evidence: /Users/oabrivard/Projects/rust/ai_synth/backend/src/services/scheduler.rs:94

• Phase-2 filtering performs per-URL DB checks (N+1 pattern).

  • Evidence: /Users/oabrivard/Projects/rust/ai_synth/backend/src/services/synthesis.rs:1031

P3

• Silent error suppression (.ok()) hides operational issues.
  • Evidence: /Users/oabrivard/Projects/rust/ai_synth/backend/src/services/synthesis.rs:351, /Users/oabrivard/Projects/rust/ai_synth/backend/src/services/synthesis.rs:457, /Users/oabrivard/Projects/rust/ai_synth/backend/src/services/synthesis.rs:604, /Users/oabrivard/Projects/rust/ai_synth/backend/src/services/scheduler.rs:67, /Users/oabrivard/Projects/rust/ai_synth/backend/src/services/scheduler.rs:85

Idiomatic Rust Assessment

• Error handling: good (AppError, Result, minimal panics).
• Layering: mostly good, but orchestration service is overloaded.
• Async/concurrency: good use of JoinSet, watch, AtomicBool.
• Testability: strong in many modules; weaker around scheduler/autonomous workflows.

Refactoring Plan

1. Correctness first (1 sprint).
   • Theme-aware import/export, theme ownership validation, update validation, defaults alignment.
2. Pipeline decomposition (1-2 sprints).
   • Split run_generation_inner into phase modules and explicit state contexts.
3. Reliability and QA hardening (1 sprint).
   • Scheduler integration tests + SSE progress integration tests.
4. Performance cleanup (incremental).
   • Batch article-history checks and optimize bulk inserts.

Quick Wins

1. Add theme ownership guard in POST /sources.
2. Add update validation for themes.
3. Wire theme_id through bulk/csv import.
4. Make export-csv honor theme_id.