Fix parameter checklist and validation attribution

- Expand 3-location to 4-location checklist: add m_global_parameters.fpp
  as required step for declaring Fortran variables (without this, adding
  a parameter to the namelist in m_start_up.fpp causes a compile error)
- Fix fastjsonschema attribution: JSON schema validation is in case.py
  and params/registry.py, not in case_validator.py which does physics
  constraint checking

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: sbryngelson

.claude/rules/parameter-system.md

@@ -9,10 +9,11 @@ MFC has ~3,300 simulation parameters defined in Python and read by Fortran via n
    - Parameters are indexed families: `patch_icpp(i)%attr`, `fluid_pp(i)%attr`, etc.
    - Each has type, default, constraints, and tags
 
-2. **Validation**: `toolchain/mfc/case_validator.py`
-   - JSON schema validation via fastjsonschema
-   - Physics constraint checking (e.g., volume fractions sum to 1)
-   - Dependency validation (required/recommended params)
+2. **Validation** (two layers):
+   - `toolchain/mfc/case.py` / `toolchain/mfc/params/registry.py` — JSON schema validation
+     via fastjsonschema (type checking, defaults)
+   - `toolchain/mfc/case_validator.py` — Physics constraint checking
+     (e.g., volume fractions sum to 1, dependency validation)
 
 3. **Input Generation**: `toolchain/mfc/run/input.py`
    - Python case dict → Fortran namelist `.inp` file
@@ -24,13 +25,15 @@ MFC has ~3,300 simulation parameters defined in Python and read by Fortran via n
 
 ## Adding a New Parameter (3-location checklist)
 
-YOU MUST update all 3 locations. Missing any causes silent failures.
+YOU MUST update all 4 locations. Missing any causes silent failures or compile errors.
 
 1. **`toolchain/mfc/params/definitions.py`**: Add parameter with type, default, constraints
-2. **`src/*/m_start_up.fpp`**: Add to the Fortran `namelist` declaration in the relevant
+2. **`src/*/m_global_parameters.fpp`**: Declare the Fortran variable in the relevant
    target(s). If the param is used by simulation only, add it there. If shared, add to
-   all three targets' m_start_up.fpp.
-3. **`toolchain/mfc/case_validator.py`**: Add validation rules if the parameter has
+   all three targets' m_global_parameters.fpp.
+3. **`src/*/m_start_up.fpp`**: Add to the Fortran `namelist` declaration in the relevant
+   target(s).
+4. **`toolchain/mfc/case_validator.py`**: Add validation rules if the parameter has
    physics constraints. Include `PHYSICS_DOCS` entry with title, category, explanation.
 
 ## Case Files

CLAUDE.md

@@ -136,10 +136,11 @@ NEVER use `stop` or `error stop`. Use `call s_mpi_abort()`.
 NEVER use `goto`, `COMMON` blocks, or global `save` variables.
 
 Every `@:ALLOCATE(...)` MUST have a matching `@:DEALLOCATE(...)`.
-Every new parameter MUST be added in 3 places:
+Every new parameter MUST be added in 4 places:
   1. `toolchain/mfc/params/definitions.py` (parameter definition)
-  2. Fortran namelist in `src/*/m_start_up.fpp` (namelist binding)
-  3. `toolchain/mfc/case_validator.py` (if constraints exist)
+  2. Fortran variable declaration in `src/*/m_global_parameters.fpp`
+  3. Fortran namelist in `src/*/m_start_up.fpp` (namelist binding)
+  4. `toolchain/mfc/case_validator.py` (if constraints exist)
 
 Changes to `src/common/` affect ALL three executables. Test comprehensively.