docs: add spec for model split — scraping vs websearch

docs/superpowers/specs/2026-03-25-model-split-design.md

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+# Design: Split Model Selection — Scraping vs Web Search
+
+**Date**: 2026-03-25
+**Scope**: Rename ai_model_writing to ai_model_websearch, split admin provider models into scraping and websearch lists
+
+---
+
+## Context
+
+Currently both model dropdowns (research + writing) show the same model list. The pipeline uses different models for different purposes: cheap/fast models for scraping and classification (Phase 1), and more capable models for web search (Phase 2). The model lists should reflect these different roles.
+
+## Changes
+
+### 1. Rename setting column
+
+```sql
+ALTER TABLE settings RENAME COLUMN ai_model_writing TO ai_model_websearch;
+```
+
+Backend: rename `ai_model_writing` → `ai_model_websearch` everywhere.
+
+### 2. Split admin_providers models JSONB
+
+Rename `models` → `models_scraping`. Add `models_websearch`.
+
+Migration updates existing provider data:
+
+**OpenAI:**
+```json
+{
+  "models_scraping": [
+    {"model_id": "gpt-4o-mini", "display_name": "GPT-4o Mini", "is_default": true},
+    {"model_id": "gpt-4.1-mini", "display_name": "GPT-4.1 Mini", "is_default": false},
+    {"model_id": "gpt-4.1-nano", "display_name": "GPT-4.1 Nano", "is_default": false}
+  ],
+  "models_websearch": [
+    {"model_id": "gpt-4o", "display_name": "GPT-4o", "is_default": true},
+    {"model_id": "gpt-4o-mini", "display_name": "GPT-4o Mini", "is_default": false},
+    {"model_id": "gpt-4.1", "display_name": "GPT-4.1", "is_default": false},
+    {"model_id": "gpt-4.1-mini", "display_name": "GPT-4.1 Mini", "is_default": false}
+  ]
+}
+```
+
+**Gemini:** both arrays get the same models (Gemini 2.5 Pro + Flash).
+
+**Anthropic:** both arrays get the same models (Claude Sonnet 4 + Haiku 3.5).
+
+### 3. Pipeline model usage
+
+- `ai_model` → used for Phase 1 (source scraping, per-article classify/summarize, link extraction)
+- `ai_model_websearch` → used for Phase 2 (web search fallback LLM call)
+
+### 4. Config endpoint
+
+`GET /api/v1/config/providers` returns both model arrays per provider so the frontend can populate the correct dropdown.
+
+### 5. Frontend
+
+- Rename "Modele d'ecriture" dropdown label → "Modele de recherche web"
+- `ai_model` dropdown populated from `models_scraping`
+- `ai_model_websearch` dropdown populated from `models_websearch`
+
+## Files to Modify
+
+- **Create:** migration — rename column + update JSONB (rename `models` → `models_scraping`, add `models_websearch`)
+- **Modify:** `backend/src/models/settings.rs` — rename `ai_model_writing` → `ai_model_websearch`
+- **Modify:** `backend/src/db/settings.rs` — rename in queries
+- **Modify:** `backend/src/models/provider.rs` — add `models_websearch` to `AdminProvider` / `ProviderModel` structs
+- **Modify:** `backend/src/db/providers.rs` — update queries for new JSONB structure
+- **Modify:** `backend/src/handlers/config.rs` — return both model arrays
+- **Modify:** `backend/src/handlers/admin.rs` — handle both model arrays in CRUD
+- **Modify:** `backend/src/services/synthesis.rs` — rename `model_writing` → `model_websearch`, use correct model per phase
+- **Modify:** `backend/src/services/prompts.rs` — update test fixture
+- **Modify:** `CLAUDE.md` — migration count
+- **Modify:** `frontend/src/types.ts` — rename field + add models_websearch to provider config type
+- **Modify:** `frontend/src/pages/Settings.tsx` — rename dropdown, split model sources
+- **Modify:** `frontend/src/i18n/fr.ts` — update label
+- **Modify:** `e2e/tests/generation-live.spec.ts` — update settings payload
+- **Modify:** `backend/tests/api_syntheses_test.rs` — update settings payload