feat(dynasty): add legitimacy signal from chronicle events

[csheldrick]

Summary

• Adds dynastyLegitimacy(state, dynastyId) — a [-1, 1] score derived from a dynasty's recent historicalEventIds, requiring no new storage
• Uses the score to shift the pretender revolt cohesion threshold by ±0.10 (range: 0.45–0.65), making dynasty history lightly influence future simulation behavior
• Inspector now shows Legitimacy: Stable / Contested / Fragile above the Dynasty Chronicle
• Headless report shows the top dynasty's legitimacy score alongside its prestige

Architecture answers (pre-implementation inspection)

Question	Answer
Where are dynasties?	state.dynasties: Record<Id, Dynasty> in GalaxyState; Dynasty.ts owns all logic
Where are chronicle events recorded?	recordDynastyEvent() in Dynasty.ts — pushes into dynasty.historicalEventIds (capped at 12)
Where are revolt decisions made?	maybePretenderRevolt() in Dynasty.ts, called from maybeLifeEvents()
Does dynasty prestige exist?	Yes — dynasty.prestige (0–100), grows with long reigns, drops on coups/extinction
Is there a legitimacy/stability field?	No prior field on Dynasty; Faction has one but is unrelated
Smallest deterministic change?	Derive a score from existing historicalEventIds and shift the revolt threshold

Behavior

dynastyLegitimacy(state, dynastyId) — pure, derived, no new storage:

• +1 per positive event: heir-born, succession, dynasty-restored, dynastic-marriage
• −1 per negative event: heir-died, succession-crisis, pretender-revolt, dynasty-extinct
• Normalized by chronicle length, clamped to [-1, 1]

Revolt threshold shift (was fixed at 0.55):

• revoltThreshold = 0.55 − legitimacy × 0.10
• High legitimacy (+1) → threshold 0.45 (revolt requires deeper instability)
• Low legitimacy (−1) → threshold 0.65 (revolt can happen at higher cohesion)

Inspector label: Stable (green) / Contested (yellow) / Fragile (red) — shown when chronicle exists.

Headless report line (new):

- Careers: 18 promotions · 11 falls · top house: Jarax (prestige 51, legitimacy +1.00)

Test results

✓ tsc --build (no type errors)
✓ eslint . (no lint errors)
✓ npm run report (determinism check passed — identical replay from same seed)

Noet advisory layer

Noet was used in advisory/cognitive mode only (no Noet source modified). Mode recommendation: Implementer. The noet cognition digest confirmed the right constraints: stay model-agnostic, keep behavior deterministic, prefer derived signals over stored state.

Dogfood receipt

• Repository root: /home/user/noet
• Branch: claude/dynasty-legitimacy-signal-4f5jqs
• Initial slice: slice-2026-06-25-032513 (advisory-only lane)
• Files changed in Noet: (none)
• Surface gate: ✓ PASS
• Hash valid: ✓ yes
• SERs: 0
• Noet source modified: no

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