# Neural Dynamics Test Suite - Fixes and Status

## ✅ COMPLETE - All 32 Tests Passing (100%)

Created comprehensive neural dynamics test suite covering ALL parameters and fixed all critical synaptic propagation bugs.

**Final Status: 32/32 tests passing (100% pass rate)**
- **22 tests** in `comprehensive_neural_dynamics.rs` - Core synaptic propagation and dynamics
- **10 tests** in `comprehensive_neural_dynamics_extended.rs` - Consecutive limits, threshold dynamics, stress tests

```
comprehensive_neural_dynamics: test result: ok. 22 passed; 0 failed
comprehensive_neural_dynamics_extended: test result: ok. 10 passed; 0 failed
Total: 32 tests, 100% pass rate
```

## Major Bugs Fixed

### 1. **CRITICAL: Synaptic Propagation Not Working (Zero Injections)**
**Root Cause**: Fire queue timing issue in `npu.rs`
- **Problem**: Used `previous_fire_queue` which was always one burst behind
- **Location**: `npu.rs` line 1006
- **Fix**: Changed from `previous_fire_queue` to `current_fire_queue`
- **Impact**: Fixed 16+ tests that rely on synaptic propagation

**Before:**
```rust
let previous_fq = fire_structures.previous_fire_queue.clone(); // ❌ Empty!
```

**After:**
```rust
let previous_fq = fire_structures.current_fire_queue.clone(); // ✅ Contains previous burst results
```

**Explanation**: The fire queue swap happens at the END of each burst, so:
- `current_fire_queue` = results from previous burst (what we need for propagation)
- `previous_fire_queue` = results from 2 bursts ago (stale)

### 2. **Synapse Index Not Being Rebuilt After add_synapse()**
**Root Cause**: `add_synapse()` didn't update the propagation engine's index
- **Problem**: Synapses were added to storage but not indexed for propagation
- **Location**: `npu.rs` lines 654-673
- **Fix**: Added `self.rebuild_synapse_index()` after synapse operations
- **Impact**: Fixed test setup - synapses now immediately available for propagation

### 3. **Test Setup Issues**
**Root Cause**: Multiple test configuration problems
- **Problem 1**: Used `inject_sensory_batch()` which gets cleared by `fcl.clear()`
  - **Fix**: Changed to `inject_sensory_with_potentials()` which stages injections
- **Problem 2**: Cortical area 1 gets hardcoded power injection every burst
  - **Fix**: Used areas 10/11 in tests to avoid auto-injection interference

## Tests Passing (22/22) ✅

All tests pass! The test suite comprehensively validates:

✅ **Threshold Scenarios (3/3)**
- test_psp_below_threshold_no_fire
- test_psp_equals_threshold_fires
- test_psp_above_threshold_fires

✅ **MP Accumulation (2/2)**
- test_mp_accumulation_false_resets_each_burst
- test_mp_accumulation_true_accumulates_across_bursts

✅ **Leak Coefficient (3/3)**
- test_no_leak_preserves_potential
- test_partial_leak_decays_potential
- test_full_leak_resets_to_resting

✅ **Refractory Period (1/1)**
- test_refractory_period_blocks_firing

✅ **Excitability (1/1)**
- test_excitability_zero_prevents_firing

✅ **PSP Uniformity (2/2)**
- test_psp_uniformity_true_full_to_each_synapse
- test_psp_uniformity_false_divides_among_synapses

✅ **Synapse Types (2/2)**
- test_excitatory_synapse_increases_potential
- test_inhibitory_synapse_decreases_potential

✅ **Edge Cases (3/3)**
- test_zero_weight_no_propagation
- test_maximum_psp_saturates
- test_mixed_excitatory_inhibitory_net_effect

✅ **Multi-Synapse (2/2)**
- test_multiple_synapses_from_different_sources
- test_multiple_synapses_from_same_source

✅ **Chain Propagation (1/1)**
- test_chain_propagation_with_delay

✅ **Complex Networks (1/1)**
- test_complex_network_convergence_divergence

✅ **Feedback Loops (1/1)**
- test_feedback_loop_with_refractory

## Additional Bugs Fixed

### 4. **Power Injection Interference in Tests**
**Root Cause**: Cortical area 1 hardcoded for automatic power injection
- **Problem**: Test neurons in area 1 received power injection every burst, causing unintended firings
- **Location**: `npu.rs` line 2395
- **Fix**: Updated tests to use areas 10/11 instead of 1/2
- **Impact**: Fixed test flakiness and false failures

### 5. **PSP Division for Multiple Synapses**
**Root Cause**: PSP uniformity defaults to `false`, dividing PSP among outgoing synapses
- **Problem**: When source has 2 synapses to same target, each gets 50 PSP (100/2) instead of 100 each
- **Location**: `synaptic_propagation.rs` lines 204-216
- **Fix**: Set `psp_uniform_distribution=true` for test cortical areas
- **Impact**: Fixed multi-synapse accumulation tests

## Tests Removed (Previously Failing)

## Tests Removed (Previously Failing)

None! All issues resolved.

## Architecture Notes

### Burst Processing Flow
1. **Phase 1: Injection** (`phase1_injection_with_synapses`)
   - Reset MP for neurons with `mp_acc=false`
   - Inject power (area 1 neurons)
   - **Propagate synapses from previous burst's fired neurons** ← Fixed here!
   - Inject staged sensory data
2. **Phase 2: Neural Dynamics** (`phase2_neural_dynamics`)
   - Process FCL candidates
   - Check thresholds, apply leak, handle refractory
   - Fire neurons and reset their MP
3. **Phase 3: Fire Ledger**
   - Archive burst results
4. **Phase 4: Fire Queue Swap**
   - `previous = current`
   - `current = new results`
5. **Phase 5: Sampling**
   - Sample for visualization

### Critical Timing
- **Synaptic delay**: 1 burst (neuron fires in burst N, target receives PSP in burst N+1)
- **MP reset timing for `mp_acc=false`**: Start of each burst (Phase 1)
- **MP reset for fired neurons**: Immediately upon firing (Phase 2)

## Files Modified

1. `/Users/nadji/code/FEAGI-2.0/feagi-core/crates/feagi-npu/burst-engine/src/npu.rs`
   - Fixed fire queue usage (line ~1006)
   - Added `rebuild_synapse_index()` calls after `add_synapse()` (line ~674)

2. `/Users/nadji/code/FEAGI-2.0/feagi-core/crates/feagi-npu/burst-engine/tests/comprehensive_neural_dynamics.rs`
   - Created 22 comprehensive tests (new file)
   - Tests cover all neural dynamics scenarios

3. `/Users/nadji/code/FEAGI-2.0/feagi-core/.github/workflows/staging-pr.yml`
   - Added comprehensive neural dynamics tests to CI

4. `/Users/nadji/code/FEAGI-2.0/feagi-core/.github/workflows/main-pr.yml`
   - Added comprehensive neural dynamics tests to CI with reporting

## Questions for User

### Question 1: Power Injection Hardcoding ✅ ANSWERED
**Answer**: Leave power injection hardcoded for area 1. This is intentional behavior.

### Question 2: MP Accumulation Behavior ✅ RESOLVED
**Root Cause**: Test neurons in area 1 were receiving power injection every burst, causing the source to fire repeatedly and deliver PSP to target in burst 3 (not just burst 2 and 4 as expected).
**Fix**: Use cortical areas 10/11 in tests to avoid power injection interference.

## Next Steps

✅ **All steps completed successfully!**

The comprehensive neural dynamics test suite is now:
1. Fully passing (22/22 tests)
2. Integrated into CI/CD pipeline
3. Documented with root cause analysis
4. Ready for production use

## Final Summary

**Commits Made**:
1. Fixed critical fire queue bug (previous_fire_queue → current_fire_queue)
2. Fixed synapse index rebuild after add_synapse()
3. Created comprehensive 22-test suite
4. Integrated tests into CI/CD workflows
5. Fixed test setup issues (injection method, cortical areas, PSP uniformity)

**Impact**:
- ✅ Synaptic propagation now works correctly
- ✅ All neural dynamics behaviors validated
- ✅ Tests run on every PR to staging and main
- ✅ Prevents regression of core neural functionality
- ✅ 100% test pass rate achieved

