Add mcp knowledge category with 5 rules

Rules derived from BC MCP API page development experience:

- api-page-flowfields-must-be-calcfields: FlowFields return empty on API
  pages unless explicitly CalcFields'd in OnAfterGetRecord
- stored-derived-fields-must-not-be-exposed-directly: Stored fields updated
  only via OnValidate triggers can be stale; recalculate live in OnAfterGetRecord
- api-page-key-fields-must-be-editable-on-insert: ODataKeyFields with
  Editable=false are rejected as unknown properties on POST
- api-page-least-privilege-write-access: Create dedicated minimal pages per
  write concern rather than widening general-purpose pages
- agent-must-not-write-business-process-status: Agents must only write
  developer-tracking fields; business status fields affect invoicing/time registration

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

custom/knowledge/mcp/api-page-key-fields-must-be-editable-on-insert.md

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+# CURABIS MCP: ODataKeyFields Must Be Editable for Create Operations
+
+## Core Principle
+
+Fields declared in `ODataKeyFields` that identify the record must not have `Editable = false` when the API page allows insert. If they are read-only, the OData API rejects them as unknown properties on POST — the create operation fails and the caller receives a `BadRequest` error.
+
+## Why This Happens
+
+`Editable = false` on a page field removes the field from the OData write schema entirely. When a consumer POSTs a new record and includes the key field in the body, BC cannot match it to any writable property and rejects the request.
+
+## Pattern to Avoid
+
+```al
+// WRONG: Key field marked Editable = false — cannot be set on create
+field(projectNo; Rec."Project No.")
+{
+    Caption = 'projectNo';
+    Editable = false;  // blocks insert via API
+}
+```
+
+## Correct Pattern
+
+```al
+// CORRECT: No Editable = false — BC controls mutability after insert via ODataKeyFields
+field(projectNo; Rec."Project No.")
+{
+    Caption = 'projectNo';
+}
+```
+
+## Requirements
+
+- Fields listed in `ODataKeyFields` must not carry `Editable = false` on pages where `InsertAllowed = true`
+- Fields that should be read-only after creation but writable on insert need no special property — OData key semantics handle immutability after the record exists
+- Non-key fields that are genuinely read-only may still use `Editable = false`
+
+## Verification
+
+On any API page with `InsertAllowed = true`, confirm that every field referenced in `ODataKeyFields` does not have `Editable = false` in its field definition. A create test via the OData endpoint is the definitive check.