# CSH2 Cryogenic Pump — Diagnostic Reasoning Chains
# Step-by-step decision trees encoding how an expert reasons from observation to diagnosis.
# Each step specifies: what tool to call, what to look for, and branching rules.

reasoning_chains:
  - id: RC-001
    name: "Low Pressure Build Diagnostic"
    trigger: "PT130 cannot reach target pressure"
    related_failure_modes: [FM-001, FM-002, FM-003, FM-007]
    steps:
      - step: 1
        action: "query_sensor_data"
        description: "Pull PT130, PT110, TT110, VFD speed for the time window"
        parameters:
          tagindices: [18, 17, 24, 13]
        look_for: "PT130 plateau level, PT110 stability, TT110 trend"
        next:
          if_pt130_below_50pct_target: "step_2"
          if_pt130_slow_build: "step_5"

      - step: 2
        action: "run_simulation"
        description: "Compute expected PT130 at current operating conditions"
        parameters_from: "extracted operating conditions"
        look_for: "Sim vs measured gap magnitude"
        next:
          if_gap_gt_20pct: "step_3"
          if_gap_lt_20pct: "step_6"

      - step: 3
        action: "Run DCV leak test"
        description: "Check PT130 decay rate with pump stopped"
        look_for: "Decay rate in bar/min"
        next:
          if_decay_gt_5_bar_per_min: "conclude_FM002"
          if_decay_lt_5_bar_per_min: "step_4"

      - step: 4
        action: "Compare pressure build at multiple speeds"
        description: "Run pump at 10%, 30%, 50% speed and compare pressure"
        look_for: "Does pressure gap worsen at higher speeds?"
        next:
          if_worse_at_higher_speed: "conclude_FM001"
          if_similar_at_all_speeds: "step_5"

      - step: 5
        action: "Check inlet conditions"
        description: "Verify subcooling margin: T_sat(PT110) - TT110"
        look_for: "Subcooling margin in K"
        next:
          if_margin_lt_2K: "conclude_FM007"
          if_margin_gt_2K: "step_6"

      - step: 6
        action: "search_domain_knowledge"
        description: "Search maintenance history for recent ICV/DCV work"
        parameters:
          category: "maintenance_history"
          component: "ICV"
        look_for: "Recent maintenance events"
        next:
          if_recent_icv_work: "conclude_FM001_installation"
          if_no_recent_work: "conclude_FM003"

    conclusions:
      conclude_FM001:
        diagnosis: "ICV reverse flow — leak worsens with speed"
        confidence: "high"
        failure_mode: FM-001
      conclude_FM001_installation:
        diagnosis: "ICV installation issue — recent maintenance"
        confidence: "high"
        failure_mode: FM-001
      conclude_FM002:
        diagnosis: "DCV leakage — static pressure decay"
        confidence: "high"
        failure_mode: FM-002
      conclude_FM003:
        diagnosis: "HP seal blowby — gradual degradation"
        confidence: "moderate"
        failure_mode: FM-003
      conclude_FM007:
        diagnosis: "Insufficient subcooling — two-phase inlet"
        confidence: "high"
        failure_mode: FM-007

  - id: RC-002
    name: "Pressure Oscillation Diagnostic"
    trigger: "PT130 showing high-frequency oscillations"
    related_failure_modes: [FM-004]
    steps:
      - step: 1
        action: "query_sensor_data"
        description: "Pull PT130 at 1-second resolution for oscillation analysis"
        parameters:
          tagindices: [18, 1]
          resolution: "1sec"
        look_for: "Oscillation frequency and amplitude"

      - step: 2
        action: "Correlate with AOV141 cycling"
        description: "Check if AOV140/141 is cycling in sync with PT130"
        look_for: "Phase correlation between pressure and valve"
        next:
          if_correlated: "conclude_FM004"
          if_not_correlated: "step_3"

      - step: 3
        action: "Check DCV dynamics"
        description: "Analyze stroke timing — DCV may be bouncing"
        look_for: "DCV open/close timing anomalies"
        next:
          default: "conclude_valve_dynamics"

    conclusions:
      conclude_FM004:
        diagnosis: "Safety loop oscillation — AOV141 hunting"
        confidence: "high"
        failure_mode: FM-004
      conclude_valve_dynamics:
        diagnosis: "DCV dynamic behavior anomaly — investigate spring force"
        confidence: "moderate"
        failure_mode: FM-002

  - id: RC-003
    name: "Elevated Discharge Temperature Diagnostic"
    trigger: "TT130 higher than isentropic prediction"
    related_failure_modes: [FM-005, FM-006]
    steps:
      - step: 1
        action: "query_sensor_data"
        description: "Pull TT130, PT130, PT110, TT110"
        parameters:
          tagindices: [27, 18, 17, 24]
        look_for: "TT130 excess above isentropic prediction"

      - step: 2
        action: "run_simulation"
        description: "Compute isentropic discharge temperature"
        look_for: "Measured TT130 vs predicted"
        next:
          if_excess_gt_20K: "step_3"
          if_excess_lt_20K: "conclude_normal_friction"

      - step: 3
        action: "Check pressure ratio"
        description: "PT130/PT110 ratio vs expected"
        look_for: "Is pressure building normally?"
        next:
          if_ratio_low: "conclude_FM005"
          if_ratio_normal: "step_4"

      - step: 4
        action: "Check TT110 trend"
        description: "Is TT110 rising during operation?"
        look_for: "TT110 rate of change"
        next:
          if_tt110_rising: "conclude_FM006"
          if_tt110_stable: "conclude_friction"

    conclusions:
      conclude_FM005:
        diagnosis: "Dry running — pump compressing gas"
        confidence: "high"
        failure_mode: FM-005
      conclude_FM006:
        diagnosis: "ICV thermal backflow — hot fluid heating inlet"
        confidence: "high"
        failure_mode: FM-006
      conclude_normal_friction:
        diagnosis: "Normal — friction heating within expected range"
        confidence: "high"
      conclude_friction:
        diagnosis: "Elevated friction — possible seal break-in or bore damage"
        confidence: "moderate"
        failure_mode: FM-003

  - id: RC-004
    name: "Reduced Flow Rate Diagnostic"
    trigger: "FT140 below expected mass flow rate"
    related_failure_modes: [FM-001, FM-002, FM-007]
    steps:
      - step: 1
        action: "query_sensor_data"
        description: "Pull FT140, PT130, VFD speed"
        parameters:
          tagindices: [7, 18, 13]
        look_for: "Flow rate vs expected at current speed"

      - step: 2
        action: "Check FT140 calibration"
        description: "Verify FT140 density correction factor is applied"
        look_for: "Is fluid H2 or N2? Apply correct density correction"
        next:
          if_calibration_wrong: "conclude_calibration_error"
          if_calibration_correct: "step_3"

      - step: 3
        action: "run_simulation"
        description: "Compute expected flow at current conditions"
        look_for: "Vol efficiency and loss breakdown"
        next:
          if_icv_leak_dominant: "conclude_FM001"
          if_dcv_leak_dominant: "conclude_FM002"
          if_gas_inlet: "conclude_FM007"

    conclusions:
      conclude_FM001:
        diagnosis: "ICV leakage reducing effective displacement"
        confidence: "high"
        failure_mode: FM-001
      conclude_FM002:
        diagnosis: "DCV leakage losing compressed fluid"
        confidence: "high"
        failure_mode: FM-002
      conclude_FM007:
        diagnosis: "Two-phase inlet reducing effective displacement"
        confidence: "high"
        failure_mode: FM-007
      conclude_calibration_error:
        diagnosis: "FT140 reading incorrect — apply density correction"
        confidence: "high"

  - id: RC-005
    name: "Motor Power Anomaly Diagnostic"
    trigger: "Motor power or current anomaly at given speed"
    related_failure_modes: [FM-003]
    steps:
      - step: 1
        action: "query_sensor_data"
        description: "Pull VFD power, current, speed, torque"
        parameters:
          tagindices: [43, 45, 13, 48]
        look_for: "Power/current at each speed point"

      - step: 2
        action: "Compare to baseline power-speed curve"
        description: "Plot power vs speed, compare to reference"
        look_for: "Offset direction"
        next:
          if_power_higher: "step_3"
          if_power_lower: "conclude_reduced_load"

      - step: 3
        action: "search_domain_knowledge"
        description: "Check seal friction baseline expectations"
        parameters:
          category: "operational_context"
        look_for: "Post-maintenance friction expectations"
        next:
          if_recent_seal_work: "conclude_seal_break_in"
          if_no_recent_work: "conclude_FM003"

    conclusions:
      conclude_FM003:
        diagnosis: "HP seal friction increasing — possible bore damage"
        confidence: "moderate"
        failure_mode: FM-003
      conclude_seal_break_in:
        diagnosis: "Normal seal break-in after maintenance (7-9 kgf → 4-5 kgf)"
        confidence: "high"
      conclude_reduced_load:
        diagnosis: "Reduced load — possible liquid starvation or low discharge pressure"
        confidence: "moderate"

  - id: RC-006
    name: "Post-Maintenance Performance Verification"
    trigger: "Performance check after maintenance event"
    related_failure_modes: [FM-001, FM-002, FM-003]
    steps:
      - step: 1
        action: "search_domain_knowledge"
        description: "Look up the maintenance event details"
        parameters:
          category: "maintenance_history"
        look_for: "What was done, what to expect"

      - step: 2
        action: "query_sensor_data"
        description: "Pull first test run after maintenance"
        look_for: "Compare to pre-maintenance baseline"

      - step: 3
        action: "run_diagnostics"
        description: "Run full D1-D8 diagnostic sweep"
        look_for: "Any new or resolved diagnostic flags"

      - step: 4
        action: "run_simulation"
        description: "Compare sim prediction to post-maintenance performance"
        look_for: "Has the residual changed after maintenance?"

    conclusions:
      conclude_improved:
        diagnosis: "Maintenance successfully addressed the issue"
        confidence: "high"
      conclude_no_change:
        diagnosis: "Maintenance did not resolve the underlying issue"
        confidence: "moderate"
      conclude_degraded:
        diagnosis: "Performance worse after maintenance — investigate installation"
        confidence: "high"