Skills: adopt RFC 2119 requirement-level language across all SKILL docs

.cursor/skills/agoda-ioc-dependency-injection/SKILL.md

@@ -5,6 +5,16 @@ description: Enforces use of Agoda.IoC attribute-based dependency injection regi
 
 # Agoda.IoC for Dependency Injection
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 Use [Agoda.IoC](https://github.com/agoda-com/Agoda.IoC) attribute-based registration in all C# **application** projects. Do NOT use it in **library/SDK** projects — libraries should not force a DI framework on their consumers.
 
 ## Why Attribute-Based Registration

.cursor/skills/api-response-for-browser/SKILL.md

@@ -5,6 +5,16 @@ description: Enforces efficient API endpoint design when serving data to browser
 
 # API Response Design for Browser Clients
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 ## Rule
 
 **Shape data on the server to match what the page needs. Minimise the number of HTTP requests per page.**

.cursor/skills/csharp-async-patterns/SKILL.md

@@ -10,6 +10,16 @@ description: >-
 
 # C# Async/Await Standards
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 ## Always use async API versions
 
 Prefer the async version of any method when it exists. No downsides.

.cursor/skills/csharp-code-style/SKILL.md

@@ -10,6 +10,16 @@ description: >-
 
 # C# Code Style Standards
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 ## Naming conventions
 
 Follow Resharper defaults for consistency.

.cursor/skills/csharp-collections/SKILL.md

@@ -11,6 +11,16 @@ description: >-
 
 # C# Collection Standards
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 ## Do not use Arrays
 
 No public method may return an Array (except `byte[]` for binary data). Use `List<T>`, `IEnumerable<T>`, `Dictionary<K,V>`, `HashSet<T>` instead. Arrays are only acceptable internally for performance-critical or raw binary scenarios.

.cursor/skills/csharp-configuration/SKILL.md

@@ -10,6 +10,16 @@ description: >-
 
 # C# Configuration Standards
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 ## Config files: only for Consul bootstrap and secrets
 
 For new projects, `web/app.config` should only contain:

.cursor/skills/csharp-exception-handling/SKILL.md

@@ -10,6 +10,16 @@ description: >-
 
 # C# Exception Handling Standards
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 ## Be specific in what you catch
 
 Catch the most specific exception type possible. Never catch `System.Exception` when you only handle a specific scenario.

.cursor/skills/csharp-extension-methods/SKILL.md

@@ -9,6 +9,16 @@ description: >-
 
 # C# Extension Method Standards
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 ## When to write an extension method
 
 Only when at least one is true:

.cursor/skills/csharp-gui-testing/SKILL.md

@@ -9,6 +9,16 @@ description: >-
 
 # C# GUI Testing Standards
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 ## Use CSS selectors, not XPath
 
 XPath is unfamiliar to most developers and adds noise. Since we identify elements with `data-selenium`, CSS selectors are sufficient.

.cursor/skills/csharp-logging/SKILL.md

@@ -8,6 +8,16 @@ description: >-
 
 # C# Logging Standards
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 ## Log message guidelines
 
 - Short but relevant messages

.cursor/skills/csharp-service-design/SKILL.md

@@ -12,6 +12,16 @@ description: >-
 
 # C# Service Design Standards
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 ## Interfaces
 
 Only create an interface if:

.cursor/skills/csharp-testing-strategy/SKILL.md

@@ -5,6 +5,16 @@ description: Enforces the Honeycomb testing strategy for C# services. Prefer bla
 
 # C# Testing Strategy
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 This skill follows the **Honeycomb testing model**: the bulk of tests should be integration tests that exercise real behavior through the HTTP boundary, not unit tests of internal classes. Unit tests are reserved for pure helper/utility methods with no dependencies.
 
 ## Test Pyramid vs Honeycomb

.cursor/skills/csharp-testing/SKILL.md

@@ -10,6 +10,16 @@ description: >-
 
 # C# Testing Standards
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 ## Why we test
 
 - Validate code does what we think it does

.cursor/skills/csharp-web-structure/SKILL.md

@@ -10,6 +10,16 @@ description: >-
 
 # C# Web Solution Structure Standards
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 ## Presentation project
 
 ### View models / DTOs

.cursor/skills/find-root-cause/SKILL.md

@@ -5,6 +5,16 @@ description: Enforces root-cause analysis before fixing bugs or resolving errors
 
 # Find the Root Cause
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 ## Core Rule
 
 **Never patch symptoms. Always find and fix the root cause.** Before writing any fix, trace the problem to its origin. A fix that suppresses the symptom without addressing why it happened will fail again — or worse, hide the real issue until it causes broader damage.

.cursor/skills/no-browser-datetime/SKILL.md

@@ -5,6 +5,16 @@ description: Enforces that Date objects and datetime types are never used in bro
 
 # No DateTime in the Browser
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 ## Rule
 
 **Never use `Date` objects or datetime types in browser/frontend code.**

.cursor/skills/no-test-code-in-production/SKILL.md

@@ -5,6 +5,16 @@ description: Enforces that mocks, stubs, fakes, and other test-only code are nev
 
 # No Test Code in Production
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 ## Core Rule
 
 Never place mocks, stubs, fakes, spy implementations, or any test-only code in production source files. Test doubles belong exclusively in test files and test directories.

.cursor/skills/preserve-existing-tests/SKILL.md

@@ -5,6 +5,16 @@ description: Prevents modification of existing tests and test data unless behavi
 
 # Preserve Existing Tests
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 ## Core Rule
 
 **Never modify existing tests or test data.** If existing tests fail after your changes, that is a signal you may have introduced a bug — not that the tests are wrong.

.cursor/skills/react-component-layout/SKILL.md

@@ -5,6 +5,16 @@ description: Enforces that React component code mirrors the visual layout of the
 
 # React Component Layout
 
+## Requirement levels (RFC 2119)
+
+The key words **MUST**, **MUST NOT**, **REQUIRED**, **SHALL**, **SHALL NOT**, **SHOULD**, **SHOULD NOT**, **RECOMMENDED**, **NOT RECOMMENDED**, **MAY**, and **OPTIONAL** in this document are to be interpreted as described in RFC 2119.
+
+Interpretation for contributors and reviewers:
+- **MUST / MUST NOT**: non-negotiable requirement (blocking)
+- **SHOULD / SHOULD NOT**: strong default; deviations require explicit rationale
+- **MAY / OPTIONAL**: context-dependent choice
+
+
 Structure React code so that reading it feels like looking at the UI. A developer should be able to glance at the JSX and immediately see the same major sections, divisions, and hierarchy that appear on screen.
 
 ## Core Principles