progression-entities

XP required follows int(100 * level^1.5) with a level cap of 99 and +5 AP per level. The _execute_level_up algorithm carries excess XP forward, grants AP, and unlocks skills at levels 2, 5, and 10 (power_strike, swift_reflexes, fireball).

Nine attributes (STR, AGI, VIT, END, INT, SPI, WIS, PER, CHA) feed exact formulas, e.g. Max_HP = base_hp + vitality*2 + int(endurance*0.5) + gear_hp. LevelingService.recalculate_combat_stats applies them in a strict 6-step order: base, equipment, passives, traits, movement cost, then tactical role.

Role flickering is prevented by a 5-point hysteresis rule: the role only switches when the new role's attribute score exceeds the current role's score by more than 5. If flickering occurs, verify the hysteresis comparison in step 6 of recalculate_combat_stats.

Four gates are checked in the apply path: PROG-067 (sufficient unspent AP), PROG-068 (valid attribute name), PROG-069 (aptitude multiplier from class/race), and PROG-070 (attribute value cap of 99).

Tests live in tests/unit/progression/, including test_leveling.py, test_attribute_growth.py, test_evolution.py, test_classes_loadouts.py, and test_progression_v2.py. These cover the XP curve, level-up execution, and class loadout base stats.