diff --git a/.github/instructions/context-engineering.instructions.md b/.github/instructions/context-engineering.instructions.md
new file mode 100644
index 000000000..99658fd52
--- /dev/null
+++ b/.github/instructions/context-engineering.instructions.md
@@ -0,0 +1,44 @@
+---
+description: 'Guidelines for structuring code and projects to maximize GitHub Copilot effectiveness through better context management'
+applyTo: '**'
+---
+
+# Context Engineering
+
+Principles for helping GitHub Copilot understand your codebase and provide better suggestions.
+
+## Project Structure
+
+- **Use descriptive file paths**: `src/auth/middleware.ts` > `src/utils/m.ts`. Copilot uses paths to infer intent.
+- **Colocate related code**: Keep components, tests, types, and hooks together. One search pattern should find everything related.
+- **Export public APIs from index files**: What's exported is the contract; what's not is internal. This helps Copilot understand boundaries.
+
+## Code Patterns
+
+- **Prefer explicit types over inference**: Type annotations are context. `function getUser(id: string): Promise<User>` tells Copilot more than `function getUser(id)`.
+- **Use semantic names**: `activeAdultUsers` > `x`. Self-documenting code is AI-readable code.
+- **Define constants**: `MAX_RETRY_ATTEMPTS = 3` > magic number `3`. Named values carry meaning.
+
+## Working with Copilot
+
+- **Keep relevant files open in tabs**: Copilot uses open tabs as context signals. Working on auth? Open auth-related files.
+- **Position cursor intentionally**: Copilot prioritizes code near your cursor. Put cursor where context matters.
+- **Use Copilot Chat for complex tasks**: Inline completions have minimal context. Chat mode sees more files.
+
+## Context Hints
+
+- **Add a COPILOT.md file**: Document architecture decisions, patterns, and conventions Copilot should follow.
+- **Use strategic comments**: At the top of complex modules, briefly describe the flow or purpose.
+- **Reference patterns explicitly**: "Follow the same pattern as `src/api/users.ts`" gives Copilot a concrete example.
+
+## Multi-File Changes
+
+- **Describe scope first**: Tell Copilot all files involved before asking for changes. "I need to update the User model, API endpoint, and tests."
+- **Work incrementally**: One file at a time, verifying each change. Don't ask for everything at once.
+- **Check understanding**: Ask "What files would you need to see?" before complex refactors.
+
+## When Copilot Struggles
+
+- **Missing context**: Open the relevant files in tabs, or explicitly paste code snippets.
+- **Stale suggestions**: Copilot may not see recent changes. Re-open files or restart the session.
+- **Generic answers**: Be more specific. Add constraints, mention frameworks, reference existing code.
diff --git a/.github/instructions/self-explanatory-code-commenting.instructions.md b/.github/instructions/self-explanatory-code-commenting.instructions.md
new file mode 100644
index 000000000..5ffa68fa8
--- /dev/null
+++ b/.github/instructions/self-explanatory-code-commenting.instructions.md
@@ -0,0 +1,162 @@
+---
+description: 'Guidelines for GitHub Copilot to write comments to achieve self-explanatory code with less comments. Examples are in JavaScript but it should work on any language that has comments.'
+applyTo: '**'
+---
+
+# Self-explanatory Code Commenting Instructions
+
+## Core Principle
+**Write code that speaks for itself. Comment only when necessary to explain WHY, not WHAT.**
+We do not need comments most of the time.
+
+## Commenting Guidelines
+
+### ❌ AVOID These Comment Types
+
+**Obvious Comments**
+```javascript
+// Bad: States the obvious
+let counter = 0;  // Initialize counter to zero
+counter++;  // Increment counter by one
+```
+
+**Redundant Comments**
+```javascript
+// Bad: Comment repeats the code
+function getUserName() {
+    return user.name;  // Return the user's name
+}
+```
+
+**Outdated Comments**
+```javascript
+// Bad: Comment doesn't match the code
+// Calculate tax at 5% rate
+const tax = price * 0.08;  // Actually 8%
+```
+
+### ✅ WRITE These Comment Types
+
+**Complex Business Logic**
+```javascript
+// Good: Explains WHY this specific calculation
+// Apply progressive tax brackets: 10% up to 10k, 20% above
+const tax = calculateProgressiveTax(income, [0.10, 0.20], [10000]);
+```
+
+**Non-obvious Algorithms**
+```javascript
+// Good: Explains the algorithm choice
+// Using Floyd-Warshall for all-pairs shortest paths
+// because we need distances between all nodes
+for (let k = 0; k < vertices; k++) {
+    for (let i = 0; i < vertices; i++) {
+        for (let j = 0; j < vertices; j++) {
+            // ... implementation
+        }
+    }
+}
+```
+
+**Regex Patterns**
+```javascript
+// Good: Explains what the regex matches
+// Match email format: username@domain.extension
+const emailPattern = /^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$/;
+```
+
+**API Constraints or Gotchas**
+```javascript
+// Good: Explains external constraint
+// GitHub API rate limit: 5000 requests/hour for authenticated users
+await rateLimiter.wait();
+const response = await fetch(githubApiUrl);
+```
+
+## Decision Framework
+
+Before writing a comment, ask:
+1. **Is the code self-explanatory?** → No comment needed
+2. **Would a better variable/function name eliminate the need?** → Refactor instead
+3. **Does this explain WHY, not WHAT?** → Good comment
+4. **Will this help future maintainers?** → Good comment
+
+## Special Cases for Comments
+
+### Public APIs
+```javascript
+/**
+ * Calculate compound interest using the standard formula.
+ * 
+ * @param {number} principal - Initial amount invested
+ * @param {number} rate - Annual interest rate (as decimal, e.g., 0.05 for 5%)
+ * @param {number} time - Time period in years
+ * @param {number} compoundFrequency - How many times per year interest compounds (default: 1)
+ * @returns {number} Final amount after compound interest
+ */
+function calculateCompoundInterest(principal, rate, time, compoundFrequency = 1) {
+    // ... implementation
+}
+```
+
+### Configuration and Constants
+```javascript
+// Good: Explains the source or reasoning
+const MAX_RETRIES = 3;  // Based on network reliability studies
+const API_TIMEOUT = 5000;  // AWS Lambda timeout is 15s, leaving buffer
+```
+
+### Annotations
+```javascript
+// TODO: Replace with proper user authentication after security review
+// FIXME: Memory leak in production - investigate connection pooling
+// HACK: Workaround for bug in library v2.1.0 - remove after upgrade
+// NOTE: This implementation assumes UTC timezone for all calculations
+// WARNING: This function modifies the original array instead of creating a copy
+// PERF: Consider caching this result if called frequently in hot path
+// SECURITY: Validate input to prevent SQL injection before using in query
+// BUG: Edge case failure when array is empty - needs investigation
+// REFACTOR: Extract this logic into separate utility function for reusability
+// DEPRECATED: Use newApiFunction() instead - this will be removed in v3.0
+```
+
+## Anti-Patterns to Avoid
+
+### Dead Code Comments
+```javascript
+// Bad: Don't comment out code
+// const oldFunction = () => { ... };
+const newFunction = () => { ... };
+```
+
+### Changelog Comments
+```javascript
+// Bad: Don't maintain history in comments
+// Modified by John on 2023-01-15
+// Fixed bug reported by Sarah on 2023-02-03
+function processData() {
+    // ... implementation
+}
+```
+
+### Divider Comments
+```javascript
+// Bad: Don't use decorative comments
+//=====================================
+// UTILITY FUNCTIONS
+//=====================================
+```
+
+## Quality Checklist
+
+Before committing, ensure your comments:
+- [ ] Explain WHY, not WHAT
+- [ ] Are grammatically correct and clear
+- [ ] Will remain accurate as code evolves
+- [ ] Add genuine value to code understanding
+- [ ] Are placed appropriately (above the code they describe)
+- [ ] Use proper spelling and professional language
+
+## Summary
+
+Remember: **The best comment is the one you don't need to write because the code is self-documenting.**
diff --git a/packages/core/src/routes/admin-media.ts b/packages/core/src/routes/admin-media.ts
index 9c97009e4..1ae8370d0 100644
--- a/packages/core/src/routes/admin-media.ts
+++ b/packages/core/src/routes/admin-media.ts
@@ -496,9 +496,9 @@ adminMediaRoutes.post('/upload', async (c) => {
         }
 
         // Extract image dimensions if it's an image
-        let width: number | undefined
-        let height: number | undefined
-        
+        let width: number | null = null
+        let height: number | null = null
+
         if (file.type.startsWith('image/') && !file.type.includes('svg')) {
           try {
             const dimensions = await getImageDimensions(arrayBuffer)
@@ -511,7 +511,7 @@ adminMediaRoutes.post('/upload', async (c) => {
 
         // Generate URLs - use public serving route
         const publicUrl = `/files/${r2Key}`
-        const thumbnailUrl = file.type.startsWith('image/') ? publicUrl : undefined
+        const thumbnailUrl = file.type.startsWith('image/') ? publicUrl : null
 
         // Save to database
         const stmt = c.env.DB.prepare(`