Phase 52: Environmental Continuity¶

Status: Complete Tests: 32 new (8 night + 10 weather + 8 comms LOS + 6 SIGINT fusion) Files modified: 7 source + 1 test fixture + 1 new test file Deficits resolved: 4 (D8, D9, Phase 5 comms LOS, Phase 17 SIGINT fusion)

Summary¶

Replaced binary environmental gates with continuous functions across 4 substeps. Night detection now uses 5-level twilight gradation instead of day/night binary. Weather affects ballistics (crosswind accuracy penalty) and sensors (ITU-R P.838 rain radar attenuation). Communications check terrain LOS with diffraction model and exempt types. Space and EW SIGINT reports fuse into unified tracks via inverse-variance weighted averaging.

52a: Night Gradation¶

_compute_night_modifiers() returns (visual_mod, thermal_mod) from IlluminationLevel
5 levels: day (1.0), civil twilight (0.8), nautical (0.5), astronomical (0.3), full night (0.2)
Thermal sensors use max(floor, visual) — barely affected at night (floor=0.8)
Replaces binary night_visual_modifier = 0.3 and additive thermal_night_bonus
Uses getattr(illum, "twilight_stage", None) for robustness with legacy mocks

Resolves: D8 (night/day binary).

52b: Weather Effects on Ballistics and Sensors¶

Wind extracted from WeatherConditions.wind (meteorological from-direction convention)
_compute_crosswind_penalty(): engagement-axis crosswind reduces crew_skill [0.7-1.0]
_compute_rain_detection_factor(): ITU-R P.838 X-band (k=0.01, alpha=1.28) attenuates radar detection range [0.1-1.0]
Three new calibration fields: night_thermal_floor, wind_accuracy_penalty_scale, rain_attenuation_factor
Rain only affects weather-independent sensors (radar/thermal/ESM); visual sensors already degraded by visibility

Design deviation from plan: Plan specified modifying ballistics.py (RK4 wind drift), detection.py (radar SNR), and formations.py (sea state spacing). Implementation applied effects in battle.py's engagement loop instead — crosswind as crew_skill modifier, rain as detection_range modifier. This is simpler and matches the existing pattern of all environmental modifiers being applied in the engagement loop. The ballistics RK4 kernel already handles wind internally for indirect fire; direct fire uses the Pk model.

Resolves: D9 (weather stops at visibility).

52c: Terrain-Based Comms LOS¶

Fixed latent AttributeError bug: code accessed result.has_los but LOSResult has visible field
Same bug fixed in c2/coordination.py (JTAC LOS check)
Added _LOS_EXEMPT_TYPES frozenset: HF, SATELLITE, VLF, ELF, WIRE, MESSENGER
Blocked LOS returns 0.25 factor (~6 dB single-obstruction diffraction loss), not 0.0
Bug was latent because _los_engine is always None at runtime — never triggered

Resolves: Phase 5 deficit (terrain-based comms LOS not implemented).

52d: Space SIGINT + EW SIGINT Fusion¶

SIGINTEngine._recent_reports buffer populated on successful intercepts
SIGINTEngine.get_recent_reports(clear=True) retrieves and optionally clears buffer
IntelFusionEngine.fuse_sigint_tracks() performs position-proximity association + inverse-variance weighted fusion
_fuse_two_reports() computes fused position: 1/sqrt(1/sigma_a^2 + 1/sigma_b^2) — always better accuracy than either individual
SimulationEngine._fuse_sigint() wired after space + EW updates in tick loop
Gated by triple null-check: requires space_engine, ew_engine, and intel_fusion_engine

Resolves: Phase 17 deficit (space SIGINT + EW SIGINT integration).

Files Changed¶

File	Action	Changes
`simulation/battle.py`	Modified	Night gradation helpers, wind extraction, crosswind penalty, rain attenuation, detection modifier rewiring
`simulation/calibration.py`	Modified	3 new fields: `night_thermal_floor`, `wind_accuracy_penalty_scale`, `rain_attenuation_factor`
`simulation/engine.py`	Modified	Added `_fuse_sigint()` method, wired after EW update
`c2/communications.py`	Modified	Fixed `has_los` -> `visible` bug, `_LOS_EXEMPT_TYPES`, diffraction model
`c2/coordination.py`	Modified	Fixed `has_los` -> `visible` bug in JTAC LOS
`detection/intel_fusion.py`	Modified	`fuse_sigint_tracks()`, `_position_distance()`, `_fuse_two_reports()`
`ew/sigint.py`	Modified	Report buffering (`_recent_reports`, `get_recent_reports()`)
`tests/unit/test_phase_12a_c2_depth.py`	Modified	Fixed mock to return `visible` instead of `has_los`
`tests/unit/test_phase52_environmental.py`	New	32 tests in 4 test classes

Lessons Learned¶

Latent bugs hide behind null guards: The has_los bug in communications.py and coordination.py was present since Phase 12a but never triggered because _los_engine is always None in production. Fixing the bug + fixing the test mock in the same commit is the right approach.
Environmental modifiers belong in the engagement loop: Applying crosswind and rain at the crew_skill / detection_range level in battle.py is simpler than modifying individual engine modules (ballistics, detection). The engagement loop is where all modifiers converge.
getattr for robustness with test mocks: Using getattr(illum, "twilight_stage", None) prevents AttributeError when test fixtures use SimpleNamespace without all fields.
Unused calibration fields are dead data: Planned night_full_modifier and comms_terrain_los_factor were schema fields with no code references. Removed during postmortem to avoid dead data.

Postmortem¶

Delivered vs Planned¶

52a: Delivered as planned. 5-level twilight gradation.
52b: Partially divergent. Wind and rain effects implemented in battle.py engagement loop (crew_skill + detection_range) rather than in ballistics.py/detection.py/formations.py. Sea state formation spacing deferred (existing sea_dispersion_modifier sufficient). Simpler and matches existing pattern.
52c: Delivered as planned + bonus bug fix in coordination.py (has_los -> visible).
52d: Delivered as planned. Report buffering + fusion method + engine wiring.
Scope: On target. 32 tests (plan said ~32).

Integration Audit¶

All 3 battle.py helpers called in engagement loop
_fuse_sigint() wired in tick loop after EW update
3/3 used calibration fields read via cal.get()
2 dead calibration fields removed during postmortem (night_full_modifier, comms_terrain_los_factor)
get_recent_reports() called from production _fuse_sigint()
fuse_sigint_tracks() called from production _fuse_sigint()
No TODO/FIXME in any modified file

Test Quality¶

Unit tests cover all edge cases: day, 4 twilight levels, zero wind, strong crosswind, headwind, zero/light/heavy rain, LOS clear/blocked, exempt types, fusion/separation
Integration tests: existing Phase 44 env subsystem tests validate end-to-end engagement loop
SIGINT buffering test uses real engine with actual emitter/collector, not mocks

Deficits Discovered¶

52b sea state formation spacing: Deferred. Existing sea_dispersion_modifier handles naval accuracy. Formation spacing wiring requires movement system changes outside scope.
Comms LOS diffraction is single-level (0.25): Plan mentioned multi-obstruction (12 dB for 2 obstructions). Current LOSResult doesn't distinguish shallow vs deep blockage. Single-level is a clear improvement over 0.0 (total block).