ai_synth/docs/superpowers/specs/2026-03-26-summary-length-design.md

Design: Configurable Summary Length

Date: 2026-03-26 Scope: Add a user setting to control summary detail level (court/moyen/detaille)

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Context

Currently, article summaries are fixed at 4-5 lines based on 500 chars of article body. Users want longer summaries to avoid opening articles when the summary is sufficient.

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1. New setting: summary_length

Column: summary_length INTEGER NOT NULL DEFAULT 3 in the settings table.

Values and their effect on the classify prompt:

Value	Label	Summary instruction	Body snippet size
1	Court	"un resume de 3 a 4 lignes"	500 chars
2	Moyen	"un resume de 6 a 8 lignes"	2000 chars
3	Detaille	"un resume de 12 a 15 lignes"	4000 chars (full scrape)

Default: 3 (Detaille) — generates comprehensive summaries by default.

Validation: value must be 1, 2, or 3.

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2. Prompt change

build_article_classify_prompt receives summary_length: i32 as a new parameter. It adjusts the prompt instruction:

• Current: "Genere un titre clair et un resume de 4 a 5 lignes."
• New: dynamically selects the line count based on summary_length

The body snippet parameter (body_snippet) is already passed by the caller — the caller controls the truncation length.

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3. Pipeline change

In synthesis.rs, the body snippet truncation in both Phase 1 and Phase 2 Brave classify loops changes from:

let body_snippet: String = body_text.chars().take(500).collect();

To a dynamic value based on settings.summary_length:

let snippet_size = match settings.summary_length {
    1 => 500,
    2 => 2000,
    _ => 4000,
};
let body_snippet: String = body_text.chars().take(snippet_size).collect();

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4. Frontend

A slider in Settings with 3 positions labeled "Court", "Moyen", "Detaille". Default position: "Detaille" (rightmost).

Placed in the generation settings section, near max_items_per_category.

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5. Files to modify

• Create: backend/migrations/20260326000023_add_summary_length.sql
• Modify: backend/src/models/settings.rs — add summary_length to UserSettings, UpdateSettingsRequest, Default, validation (1-3)
• Modify: backend/src/db/settings.rs — add summary_length to SettingsRow, queries, binds
• Modify: backend/src/services/prompts.rs — build_article_classify_prompt takes summary_length, adjusts instruction
• Modify: backend/src/services/synthesis.rs — dynamic snippet size based on settings.summary_length
• Modify: frontend/src/types.ts — add summary_length: number to UserSettings and DEFAULT_SETTINGS
• Modify: frontend/src/pages/Settings.tsx — add slider component
• Modify: frontend/src/i18n/fr.ts — labels for slider
• Modify: CLAUDE.md — migration count
• Modify: backend/src/services/prompts.rs tests — update test_settings() fixture, add test for summary_length
• Modify: backend/tests/api_syntheses_test.rs — add summary_length to settings payload
• Modify: backend/tests/pipeline_test.rs — add summary_length to settings payload
• Modify: e2e/tests/generation-live.spec.ts — add summary_length to settings payload