diff --git a/revdep/.gitignore b/revdep/.gitignore
index a2b0d9bb97..b06d4d8201 100644
--- a/revdep/.gitignore
+++ b/revdep/.gitignore
@@ -1,3 +1,4 @@
 /cloud.noindex
 /cloud
 /review/
+/notifications/
diff --git a/revdep/NOTIFY-README.md b/revdep/NOTIFY-README.md
new file mode 100644
index 0000000000..bf219ed9d6
--- /dev/null
+++ b/revdep/NOTIFY-README.md
@@ -0,0 +1,131 @@
+# Maintainer Notification Script
+
+This script (`notify-maintainers.sh`) automates the process of notifying package maintainers about reverse dependency issues discovered during igraph development.
+
+## Features
+
+- **GitHub Integration**: Automatically creates GitHub issues for packages hosted on GitHub
+- **Email Fallback**: Generates email drafts for packages not on GitHub or when GitHub access fails
+- **Template-based**: Creates well-formatted issue descriptions with all relevant information
+
+## Prerequisites
+
+### For GitHub Issues (Optional)
+
+```bash
+# Install GitHub CLI
+# On macOS:
+brew install gh
+
+# On Linux:
+# See https://github.com/cli/cli#installation
+
+# Authenticate with GitHub
+gh auth login
+```
+
+### For Email Drafts
+
+No additional setup required - the script will generate email templates that can be manually sent.
+
+## Usage
+
+```bash
+./notify-maintainers.sh
+```
+
+The script will:
+
+1. Check if `gh` CLI is available
+2. For each package (Cascade, jewel, rSpectral):
+   - Check if the GitHub repository is accessible
+   - If accessible: Create a GitHub issue directly using `gh issue create`
+   - If not accessible: Create an email draft in `notifications/`
+
+The script determines upfront which action to take and only creates the appropriate output (either GitHub issue OR email draft, not both).
+
+## Output
+
+Files are created in the `notifications/` directory **only for packages that require email drafts**:
+
+- `{Package}-email.txt` - Complete email draft with subject and body
+
+For packages with accessible GitHub repositories, issues are created directly and no local files are saved.
+
+## Manual Steps
+
+### If GitHub Issues Fail
+
+If you see authentication or permission errors when creating GitHub issues:
+
+1. Check GitHub authentication: `gh auth status`
+2. Authenticate if needed: `gh auth login`
+3. Or manually create issues by viewing the error output and creating them through the GitHub web interface
+2. Click "Issues" → "New Issue"
+3. Copy the content from `notifications/{Package}-issue.md`
+
+### For Email Drafts
+
+When GitHub repositories are not accessible, email drafts are automatically generated. To send these emails:
+
+1. Review the email content in `notifications/{Package}-email.txt`
+2. Copy the content
+3. Create a new email in your email client
+4. Update the "To:" field with the actual maintainer email (check CRAN package page)
+5. Paste the subject and body
+6. Send the email
+
+## Package Information
+
+### Cascade
+- **GitHub**: https://github.com/fbertran/Cascade
+- **Issue**: Namespace collision warning
+- **Severity**: Minor
+
+### jewel
+- **GitHub**: https://github.com/annaplaksienko/jewel
+- **Issue**: Integer validation error
+- **Severity**: High
+
+### rSpectral
+- **GitHub**: https://github.com/cmclean5/rSpectral
+- **Issue**: Modularity test failures
+- **Severity**: Medium
+
+## Customization
+
+To modify the issue templates or add more packages, edit the script directly. Each package section follows this pattern:
+
+```bash
+PACKAGE="PackageName"
+GITHUB_URL="https://github.com/owner/repo"
+VERSION="x.y.z"
+ISSUE_TYPE="Description"
+SEVERITY="High/Medium/Low"
+
+cat > "$OUTPUT_DIR/${PACKAGE}-issue.md" << 'EOF'
+# Issue title
+
+Issue description...
+EOF
+```
+
+## Troubleshooting
+
+### "gh CLI not found"
+Install the GitHub CLI as described in Prerequisites.
+
+### "Failed to create issue"
+- Check GitHub authentication: `gh auth status`
+- Ensure you have permission to create issues in the repository
+- The repository may have issues disabled
+
+### "GitHub repository not accessible"
+- The repository might be private
+- The repository URL might be incorrect
+- Use the email draft fallback instead
+
+## See Also
+
+- [problems-analysis.md](problems-analysis.md) - Detailed analysis of each issue
+- [examples/](examples/) - Runnable reproduction scripts
diff --git a/revdep/examples/README.md b/revdep/examples/README.md
new file mode 100644
index 0000000000..510d4d899e
--- /dev/null
+++ b/revdep/examples/README.md
@@ -0,0 +1,38 @@
+# Reverse Dependency Problem Examples
+
+This directory contains minimal reproducible examples for the three packages that have newly broken checks compared to the most recent CRAN version of igraph.
+
+## Files
+
+- **`cascade-circulant-issue.R`** - Demonstrates the namespace collision between `igraph::circulant` and `magic::circulant`
+- **`jewel-integer-issue.R`** - Demonstrates the strict integer validation error in `rewire_impl()`
+- **`rspectral-modularity-issue.R`** - Demonstrates the automatic weight usage in modularity calculations
+
+## Running the Examples
+
+Each example is a standalone R script that can be run with:
+
+```r
+Rscript cascade-circulant-issue.R
+Rscript jewel-integer-issue.R
+Rscript rspectral-modularity-issue.R
+```
+
+Or from within R:
+
+```r
+pkgload::load_all()  # Load the development version of igraph
+source("revdep/examples/cascade-circulant-issue.R")
+source("revdep/examples/jewel-integer-issue.R")
+source("revdep/examples/rspectral-modularity-issue.R")
+```
+
+## Summary of Issues
+
+| Package | Issue | Severity | Type |
+|---------|-------|----------|------|
+| Cascade | Namespace collision warning | Low | Inadvertent behavior change |
+| jewel | Integer validation error | High | Uncovered downstream bug |
+| rSpectral | Modularity test failures | Medium | Breaking change |
+
+See `../problems-analysis.md` for detailed analysis and recommendations.
diff --git a/revdep/examples/cascade-circulant-issue.R b/revdep/examples/cascade-circulant-issue.R
new file mode 100644
index 0000000000..bc6d4a6902
--- /dev/null
+++ b/revdep/examples/cascade-circulant-issue.R
@@ -0,0 +1,36 @@
+#!/usr/bin/env Rscript
+# Minimal reproducible example for Cascade namespace collision issue
+# Issue: Warning when loading both igraph and magic packages
+
+cat("=== Cascade Namespace Collision Issue ===\n\n")
+
+# Load igraph (which now exports circulant)
+library(igraph)
+cat("Loaded igraph\n")
+cat("igraph exports circulant:", "circulant" %in% ls("package:igraph"), "\n\n")
+
+# Show that igraph::circulant exists as a constructor spec
+cat("igraph::circulant is exported as a constructor spec\n")
+cat("It is meant to be used with make_graph(), but make_graph() is deprecated\n")
+cat("Example: make_graph(circulant(10, c(1, 3)))\n\n")
+
+# Demonstrate the preferred way
+cat("Preferred way (using make_circulant directly):\n")
+g2 <- make_circulant(10, c(1, 3))
+cat("Created graph with make_circulant:", vcount(g2), "vertices,", ecount(g2), "edges\n\n")
+
+# Simulate what happens when magic package is loaded
+cat("Attempting to demonstrate namespace collision:\n")
+cat("If the magic package were loaded, it would show:\n")
+cat("  Warning: replacing previous import 'igraph::circulant' by 'magic::circulant'\n\n")
+
+cat("Root cause:\n")
+cat("- igraph added make_circulant() and its constructor alias circulant() in v2.2.1.9003\n")
+cat("- magic package also has a circulant() function for creating circulant matrices\n")
+cat("- When both packages are loaded, there's a namespace collision\n\n")
+
+cat("Assessment:\n")
+cat("- This is an inadvertent behavior change in igraph\n")
+cat("- The circulant() function is primarily a constructor alias\n")
+cat("- Users should use make_circulant() directly\n")
+cat("- Cascade package can resolve by explicitly importing magic::circulant\n")
diff --git a/revdep/examples/jewel-integer-issue.R b/revdep/examples/jewel-integer-issue.R
new file mode 100644
index 0000000000..e1c721d7ce
--- /dev/null
+++ b/revdep/examples/jewel-integer-issue.R
@@ -0,0 +1,70 @@
+#!/usr/bin/env Rscript
+# Minimal reproducible example for jewel integer validation issue
+# Issue: rewire_impl now strictly validates that n is an integer
+
+cat("=== jewel Integer Validation Issue ===\n\n")
+
+library(igraph)
+
+# Create a simple graph for testing
+g <- make_ring(10)
+cat("Created test graph:", vcount(g), "vertices,", ecount(g), "edges\n\n")
+
+# Test 1: Integer value (should work)
+cat("Test 1: Using integer value (100)\n")
+tryCatch({
+  result <- rewire(g, keeping_degseq(niter = 100))
+  cat("✓ SUCCESS: Integer value works\n")
+  cat("  Result:", vcount(result), "vertices,", ecount(result), "edges\n\n")
+}, error = function(e) {
+  cat("✗ FAILED:", conditionMessage(e), "\n\n")
+})
+
+# Test 2: Non-integer value (will fail)
+cat("Test 2: Using non-integer value (2.45)\n")
+tryCatch({
+  result <- rewire(g, keeping_degseq(niter = 2.45))
+  cat("✓ SUCCESS: Non-integer value works\n")
+  cat("  Result:", vcount(result), "vertices,", ecount(result), "edges\n\n")
+}, error = function(e) {
+  cat("✗ FAILED:", conditionMessage(e), "\n\n")
+})
+
+# Test 3: Computed value (simulating jewel package scenario)
+cat("Test 3: Using computed value (p * 0.05 where p = 49)\n")
+p <- 49
+niter <- p * 0.05  # = 2.45
+cat("  Computed niter =", niter, "\n")
+tryCatch({
+  result <- rewire(g, keeping_degseq(niter = niter))
+  cat("✓ SUCCESS: Computed value works\n")
+  cat("  Result:", vcount(result), "vertices,", ecount(result), "edges\n\n")
+}, error = function(e) {
+  cat("✗ FAILED:", conditionMessage(e), "\n\n")
+})
+
+# Test 4: Workaround using as.integer (should work)
+cat("Test 4: Using as.integer() workaround\n")
+cat("  Computed niter =", niter, "-> as.integer(niter) =", as.integer(niter), "\n")
+tryCatch({
+  result <- rewire(g, keeping_degseq(niter = as.integer(niter)))
+  cat("✓ SUCCESS: Integer conversion works\n")
+  cat("  Result:", vcount(result), "vertices,", ecount(result), "edges\n\n")
+}, error = function(e) {
+  cat("✗ FAILED:", conditionMessage(e), "\n\n")
+})
+
+cat("Root cause:\n")
+cat("- rewire_impl() converts n with as.numeric(), preserving fractional parts\n")
+cat("- C code in rinterface_extra.c now strictly validates integer values\n")
+cat("- Previously may have silently truncated, now explicitly rejects\n\n")
+
+cat("Assessment:\n")
+cat("- This uncovered a bug in the jewel package\n")
+cat("- niter should logically be an integer (number of iterations)\n")
+cat("- jewel should use ceiling(), floor(), or round() on computed niter\n\n")
+
+cat("Recommendation:\n")
+cat("- Fix in jewel: niter <- ceiling(p * 0.05)\n")
+cat("- OR fix in igraph for backward compatibility:\n")
+cat("  Add as.integer() in rewire_keeping_degseq() before calling rewire_impl()\n")
diff --git a/revdep/examples/rspectral-modularity-issue.R b/revdep/examples/rspectral-modularity-issue.R
new file mode 100644
index 0000000000..ca1c92cf12
--- /dev/null
+++ b/revdep/examples/rspectral-modularity-issue.R
@@ -0,0 +1,75 @@
+#!/usr/bin/env Rscript
+# Minimal reproducible example for rSpectral modularity issue
+# Issue: Modularity values have changed slightly
+
+cat("=== rSpectral Modularity Calculation Issue ===\n\n")
+
+library(igraph)
+
+# Create a test graph
+cat("Creating test graph...\n")
+g <- make_full_graph(5) + make_full_graph(5) + make_full_graph(5)
+cat("Graph:", vcount(g), "vertices,", ecount(g), "edges\n\n")
+
+# Test modularity with clear community structure
+membership <- c(1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3)
+
+cat("Test 1: Modularity without weights\n")
+mod1 <- modularity(g, membership, weights = NULL)
+cat("  Modularity:", mod1, "\n\n")
+
+cat("Test 2: Modularity with default (may use weights if present)\n")
+mod2 <- modularity(g, membership)
+cat("  Modularity:", mod2, "\n\n")
+
+# Add weights to demonstrate the issue
+cat("Test 3: Adding edge weights to graph\n")
+E(g)$weight <- 1.0
+cat("  Added uniform weights of 1.0\n")
+mod3 <- modularity(g, membership)
+cat("  Modularity with weights:", mod3, "\n\n")
+
+# Different weights
+cat("Test 4: Using random edge weights\n")
+set.seed(42)
+E(g)$weight <- runif(ecount(g))
+mod4 <- modularity(g, membership)
+cat("  Modularity with random weights:", mod4, "\n\n")
+
+cat("Test 5: Explicitly passing weights = NULL (doesn't disable auto-detection!)\n")
+mod5 <- modularity(g, membership, weights = NULL)
+cat("  Modularity (weights = NULL):", mod5, "\n")
+cat("  Note: This does NOT match Test 1 because weights = NULL doesn't disable auto-detection!\n")
+cat("  The function still uses the 'weight' attribute if it exists.\n\n")
+
+cat("Test 6: WORKAROUND - Using weights = numeric() to disable auto-detection\n")
+mod6 <- modularity(g, membership, weights = numeric())
+cat("  Modularity (weights = numeric()):", mod6, "\n")
+cat("  Note: This DOES match Test 1! The workaround works!\n")
+cat("  numeric() is not NULL, so auto-detection is skipped\n")
+cat("  Then !all(is.na(numeric())) is FALSE, so weights gets set to NULL internally\n\n")
+
+cat("Root cause:\n")
+cat("- igraph v2.2.1.9004 added: 'Use \"weights\" edge attribute in modularity() if available'\n")
+cat("- modularity() now automatically uses edge weights if present\n")
+cat("- Previously may have ignored weights by default\n")
+cat("- rSpectral tests also show: 'This graph was created by an old(er) igraph version'\n\n")
+
+cat("Assessment:\n")
+cat("- This is likely an inadvertent behavior change in igraph\n")
+cat("- Modularity differences are small but significant for exact tests\n")
+cat("- Expected: 0.408, Actual: 0.432 (difference: +0.024)\n")
+cat("- Expected: 0.3776, Actual: 0.3758 (difference: -0.0018)\n\n")
+
+cat("Recommendation for rSpectral:\n")
+cat("1. Update saved graph objects using upgrade_graph()\n")
+cat("2. Review whether graphs should have weights or not\n")
+cat("3. WORKAROUND: Use weights = numeric() to get unweighted modularity\n")
+cat("   Example: modularity(g, membership, weights = numeric())\n")
+cat("4. Or remove unintended weights: g <- delete_edge_attr(g, 'weight')\n")
+cat("5. Update expected test values if the new weighted modularity is correct\n\n")
+
+cat("Recommendation for igraph:\n")
+cat("1. Document weights = numeric() as the official workaround\n")
+cat("2. Or fix so that weights = NULL explicitly disables auto-detection\n")
+cat("3. Or clearly document this as a breaking change in NEWS.md\n")
diff --git a/revdep/notify-maintainers.sh b/revdep/notify-maintainers.sh
new file mode 100755
index 0000000000..de02148747
--- /dev/null
+++ b/revdep/notify-maintainers.sh
@@ -0,0 +1,329 @@
+#!/bin/bash
+# Script to notify package maintainers about reverse dependency issues
+# This script creates GitHub issues for packages hosted on GitHub
+# or creates Gmail draft emails for packages not on GitHub
+
+set -e
+
+# Check if gh CLI is available
+if ! command -v gh &> /dev/null; then
+    echo "Warning: gh CLI not found. Will only create email drafts."
+    GH_AVAILABLE=0
+else
+    GH_AVAILABLE=1
+fi
+
+# Function to check if a GitHub repo exists and is accessible
+check_github_repo() {
+    local repo=$1
+    if [ $GH_AVAILABLE -eq 0 ]; then
+        return 1
+    fi
+    
+    # Extract owner/repo from URL
+    local owner_repo=$(echo "$repo" | sed 's|https://github.com/||' | sed 's|\.git$||')
+    
+    # Check if repo is accessible
+    if gh repo view "$owner_repo" &> /dev/null; then
+        echo "$owner_repo"
+        return 0
+    else
+        return 1
+    fi
+}
+
+# Function to create a GitHub issue
+create_github_issue() {
+    local package=$1
+    local owner_repo=$2
+    local title=$3
+    local body=$4
+    
+    echo "  Creating GitHub issue..."
+    
+    # Create temporary file for issue body
+    local temp_file=$(mktemp)
+    echo "$body" > "$temp_file"
+    
+    # Create the issue
+    if gh issue create \
+        --repo "$owner_repo" \
+        --title "$title" \
+        --body-file "$temp_file" \
+        --label "bug" 2>/dev/null; then
+        echo "  ✓ Issue created successfully"
+    else
+        echo "  ⚠ Failed to create issue (may need authentication or permissions)"
+    fi
+    
+    rm -f "$temp_file"
+}
+
+# Function to create an email draft
+create_email_draft() {
+    local package=$1
+    local subject=$2
+    local body=$3
+    local email_file=$4
+    
+    echo "  Creating email draft..."
+    
+    cat > "$email_file" << EOF
+To: CRAN maintainer for $package
+Subject: $subject
+
+Dear $package Maintainer,
+
+$body
+
+Best regards,
+igraph Development Team
+EOF
+    
+    echo "  ✓ Email draft saved to: $email_file"
+}
+
+# Directory for output files
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+OUTPUT_DIR="$SCRIPT_DIR/notifications"
+mkdir -p "$OUTPUT_DIR"
+
+echo "=== Notifying Package Maintainers about Reverse Dependency Issues ==="
+echo ""
+
+# Package 1: Cascade
+PACKAGE="Cascade"
+GITHUB_URL="https://github.com/fbertran/Cascade"
+
+ISSUE_BODY='# Namespace collision warning with igraph 2.2.1.9003+
+
+## Summary
+
+When loading the Cascade package with igraph version 2.2.1.9003 or later, the following warning appears:
+
+```
+Warning: replacing previous import '"'"'igraph::circulant'"'"' by '"'"'magic::circulant'"'"' when loading '"'"'Cascade'"'"'
+```
+
+## Root Cause
+
+igraph recently added a new function `make_circulant()` and its constructor alias `circulant()` in version 2.2.1.9003. This creates a namespace collision with the `magic::circulant()` function that Cascade also imports.
+
+## Impact
+
+This is a **minor** issue - it produces a warning but does not prevent Cascade from working correctly.
+
+## Suggested Fix
+
+To resolve this warning, you can explicitly import `magic::circulant` in your NAMESPACE file:
+
+```r
+importFrom(magic, circulant)
+```
+
+This will ensure that `magic::circulant` takes precedence and the warning will not appear.
+
+## Additional Information
+
+- **igraph version with issue**: 2.2.1.9003+
+- **Cascade version tested**: 2.3
+- **Severity**: Minor (warning only, no functionality broken)
+
+This issue was discovered during reverse dependency checking for igraph. For more details, see the igraph repository.
+
+## References
+
+- igraph change: Added `make_circulant()` to expose `igraph_circulant()` (#1563, #2407)
+- igraph repository: https://github.com/igraph/rigraph'
+
+echo "Package: $PACKAGE"
+if owner_repo=$(check_github_repo "$GITHUB_URL"); then
+    echo "  ✓ GitHub repository accessible: $owner_repo"
+    create_github_issue "$PACKAGE" "$owner_repo" "Namespace collision warning with igraph 2.2.1.9003+" "$ISSUE_BODY"
+else
+    echo "  ✗ GitHub repository not accessible"
+    create_email_draft "$PACKAGE" "Namespace collision warning with igraph 2.2.1.9003+ in Cascade" "$ISSUE_BODY" "$OUTPUT_DIR/${PACKAGE}-email.txt"
+fi
+echo ""
+
+# Package 2: jewel
+PACKAGE="jewel"
+GITHUB_URL="https://github.com/annaplaksienko/jewel"
+
+ISSUE_BODY='# Integer validation error with igraph 2.2.1.9003+
+
+## Summary
+
+The jewel package fails with igraph version 2.2.1.9003 or later due to strict integer validation:
+
+```
+Error in rewire_impl(rewire = graph, n = niter, mode = mode) : 
+  At rinterface_extra.c:83 : The value 2.4500000000000002 is not representable as an integer. Invalid value
+```
+
+## Root Cause
+
+The `generateData_rewire()` function (or similar code) passes non-integer values to igraph'"'"'s `rewire()` function for the `niter` parameter. Previous versions of igraph silently truncated these values, but newer versions strictly validate that numeric values are representable as integers.
+
+## Minimal Reproducible Example
+
+```r
+library(igraph)
+g <- make_ring(10)
+
+# This now fails
+rewire(g, keeping_degseq(niter = 2.45))
+# Error: The value 2.4500000000000002 is not representable as an integer
+```
+
+## Impact
+
+This is a **high severity** issue - it causes the package to fail completely during examples and likely in actual usage.
+
+## Suggested Fix
+
+Ensure that `niter` values are integers before passing to `rewire()`:
+
+```r
+# Instead of:
+niter <- p * 0.05
+
+# Use:
+niter <- ceiling(p * 0.05)  # or floor() or round(), depending on desired behavior
+```
+
+## Example from jewel code
+
+Looking at the error message, this likely occurs in code like:
+
+```r
+# Problematic:
+n <- 49
+niter <- n * 0.05  # = 2.45
+rewire(graph, keeping_degseq(niter = niter))
+
+# Fixed:
+niter <- ceiling(n * 0.05)  # = 3
+rewire(graph, keeping_degseq(niter = niter))
+```
+
+## Additional Information
+
+- **igraph version with issue**: 2.2.1.9003+
+- **jewel version tested**: 2.0.2
+- **Severity**: High (package functionality broken)
+
+This issue was discovered during reverse dependency checking for igraph. For more details and a complete minimal reproducible example, see the igraph repository.
+
+## References
+
+- igraph repository: https://github.com/igraph/rigraph
+- Related to stricter integer validation in igraph C code'
+
+echo "Package: $PACKAGE"
+if owner_repo=$(check_github_repo "$GITHUB_URL"); then
+    echo "  ✓ GitHub repository accessible: $owner_repo"
+    create_github_issue "$PACKAGE" "$owner_repo" "Integer validation error with igraph 2.2.1.9003+" "$ISSUE_BODY"
+else
+    echo "  ✗ GitHub repository not accessible"
+    create_email_draft "$PACKAGE" "Integer validation error with igraph 2.2.1.9003+ in jewel" "$ISSUE_BODY" "$OUTPUT_DIR/${PACKAGE}-email.txt"
+fi
+echo ""
+
+# Package 3: rSpectral
+PACKAGE="rSpectral"
+GITHUB_URL="https://github.com/cmclean5/rSpectral"
+
+ISSUE_BODY='# Modularity test failures with igraph 2.2.1.9004+
+
+## Summary
+
+rSpectral tests fail with igraph version 2.2.1.9004 or later due to changes in modularity calculation behavior:
+
+```
+Expected `c$modularity` to equal `exp_mod10`.
+Differences:
+  `actual`: 0.432
+`expected`: 0.408
+```
+
+## Root Cause
+
+igraph v2.2.1.9004 changed `modularity()` to automatically use the `"weight"` edge attribute if present:
+
+```r
+if (is.null(weights) && "weight" %in% edge_attr_names(graph)) {
+  weights <- E(graph)$weight
+}
+```
+
+This means graphs with a "weight" attribute now compute weighted modularity by default, even when `weights = NULL` is explicitly passed.
+
+## Impact
+
+This is a **medium severity** issue - tests fail but core functionality may still work. The modularity values are close but not exact.
+
+## Workaround Available
+
+A simple workaround exists: pass `weights = numeric()` to force unweighted modularity calculation:
+
+```r
+# Instead of:
+modularity(g, membership)
+# or
+modularity(g, membership, weights = NULL)
+
+# Use:
+modularity(g, membership, weights = numeric())
+```
+
+This works because `numeric()` is not `NULL` (skips auto-detection), but `!all(is.na(numeric()))` evaluates to `FALSE`, causing the code to set `weights <- NULL` internally.
+
+## Suggested Fixes
+
+Choose one of the following approaches:
+
+1. **Quick fix**: Use the workaround above in places where unweighted modularity is needed
+2. **Update graph objects**: Call `igraph::upgrade_graph()` on saved graph objects
+3. **Remove unintended weights**: If graphs shouldn'"'"'t have weights, remove them:
+   ```r
+   g <- delete_edge_attr(g, "weight")
+   ```
+4. **Update test expectations**: If weighted modularity is correct, update expected values in tests
+
+## Additional Information
+
+- **igraph version with issue**: 2.2.1.9004+
+- **rSpectral version tested**: 1.0.0.10
+- **Severity**: Medium (tests fail, but workaround available)
+- **Test message**: "This graph was created by an old(er) igraph version"
+
+This issue was discovered during reverse dependency checking for igraph. For more details, complete examples, and explanation of the workaround mechanism, see the igraph repository.
+
+## References
+
+- igraph repository: https://github.com/igraph/rigraph
+- igraph change: "Use '"'"'weights'"'"' edge attribute in modularity() if available"'
+
+echo "Package: $PACKAGE"
+if owner_repo=$(check_github_repo "$GITHUB_URL"); then
+    echo "  ✓ GitHub repository accessible: $owner_repo"
+    create_github_issue "$PACKAGE" "$owner_repo" "Modularity test failures with igraph 2.2.1.9004+" "$ISSUE_BODY"
+else
+    echo "  ✗ GitHub repository not accessible"
+    create_email_draft "$PACKAGE" "Modularity test failures with igraph 2.2.1.9004+ in rSpectral" "$ISSUE_BODY" "$OUTPUT_DIR/${PACKAGE}-email.txt"
+fi
+echo ""
+
+echo "=== Summary ==="
+echo "Output directory: $OUTPUT_DIR"
+echo ""
+if [ -n "$(ls -A $OUTPUT_DIR 2>/dev/null)" ]; then
+    echo "Files created:"
+    ls -1 "$OUTPUT_DIR"
+else
+    echo "All notifications sent via GitHub issues (no local files created)"
+fi
+echo ""
+echo "Note: For GitHub issues created, check the repository issue trackers."
+echo "For email drafts, review and send the files in $OUTPUT_DIR"
diff --git a/revdep/problems-analysis.md b/revdep/problems-analysis.md
new file mode 100644
index 0000000000..03422811a2
--- /dev/null
+++ b/revdep/problems-analysis.md
@@ -0,0 +1,236 @@
+# Analysis of Reverse Dependency Problems
+
+This document provides minimal reproducible examples and analysis for the three packages that now fail their checks compared to the most recent CRAN version.
+
+**Note**: Runnable R scripts demonstrating each issue can be found in the `examples/` directory.
+
+## Summary
+
+Three packages have newly broken checks:
+1. **Cascade** (v2.3): Namespace collision warning
+2. **jewel** (v2.0.2): Error due to strict integer validation
+3. **rSpectral** (v1.0.0.10): Test failures due to modularity calculation changes
+
+## 1. Cascade - Namespace Collision Warning
+
+### Issue
+```
+Warning: replacing previous import 'igraph::circulant' by 'magic::circulant' when loading 'Cascade'
+```
+
+### Root Cause
+igraph recently added a new function `make_circulant()` (and its constructor alias `circulant()`) in version 2.2.1.9003. This creates a namespace collision with the `magic::circulant()` function that the Cascade package also uses.
+
+From NEWS.md:
+```
+# igraph 2.2.1.9003
+- Add `make_circulant()` to expose `igraph_circulant()` (#1563, #2407).
+```
+
+### Assessment
+**This is an inadvertent behavior change in igraph, not a bug in Cascade.**
+
+The `circulant` function is exported from igraph but is primarily a constructor alias (used as `graph(circulant(...))`). The main function users should use is `make_circulant()`.
+
+### Recommendation
+The `circulant` constructor alias could potentially be unexported to avoid this namespace collision, as users should be using `make_circulant()` directly. However, this would be a breaking change for users already using the constructor form.
+
+Alternatively, this is a minor warning that doesn't prevent Cascade from working, and Cascade package maintainers could resolve it by explicitly importing `magic::circulant` in their NAMESPACE.
+
+## 2. jewel - Integer Validation Error
+
+### Issue
+```
+Error in rewire_impl(rewire = graph, n = niter, mode = mode) : 
+  At rinterface_extra.c:83 : The value 2.4500000000000002 is not representable as an integer. Invalid value
+```
+
+### Minimal Reproducible Example
+```r
+library(igraph)
+g <- make_ring(10)
+
+# This works (integer value)
+rewire(g, keeping_degseq(niter = 100))  # SUCCESS
+
+# This fails (non-integer value)
+rewire(g, keeping_degseq(niter = 2.45))  # ERROR
+
+# The jewel package computes niter dynamically, e.g., p * 0.05 where p=49
+p <- 49
+niter <- p * 0.05  # = 2.45
+rewire(g, keeping_degseq(niter = niter))  # ERROR
+```
+
+### Root Cause
+The `rewire_impl()` function in `R/aaa-auto.R` converts the `n` parameter using `as.numeric()`:
+
+```r
+rewire_impl <- function(rewire, n, mode = c("simple", "simple_loops")) {
+  ensure_igraph(rewire)
+  n <- as.numeric(n)  # This preserves non-integer values
+  mode <- switch_igraph_arg(mode, "simple" = 0L, "simple_loops" = 1L)
+  # ...
+  res <- .Call(R_igraph_rewire, rewire, n, mode)
+}
+```
+
+However, the C code in `src/rinterface_extra.c` now strictly validates that numeric values are representable as integers:
+
+```c
+if (((igraph_integer_t) REAL(value)[0]) != REAL(value)[0]) {
+  igraph_errorf("The value %.17g is not representable as an integer.",
+                __FILE__, __LINE__, IGRAPH_EINVAL, REAL(value)[0]);
+}
+```
+
+Previously, the C code may have silently truncated or rounded non-integer values, but now it explicitly rejects them.
+
+### Assessment
+**This is a behavior change in igraph that uncovered a bug in the jewel package.**
+
+The `niter` parameter should logically be an integer (number of iterations), and the jewel package should be rounding or truncating the computed value. However, igraph's stricter validation now makes this explicit.
+
+### Recommendation
+The fix should be in the jewel package - they should ensure `niter` is an integer:
+```r
+niter <- ceiling(p * 0.05)  # or floor() or round()
+```
+
+However, igraph could be more user-friendly by automatically rounding the value in `rewire_keeping_degseq()` before passing to `rewire_impl()`:
+
+```r
+rewire_keeping_degseq <- function(graph, loops, niter) {
+  loops <- as.logical(loops)
+  niter <- as.integer(niter)  # Add explicit integer conversion
+  mode <- if (loops) "simple_loops" else "simple"
+  
+  rewire_impl(
+    rewire = graph,
+    n = niter,
+    mode = mode
+  )
+}
+```
+
+This would maintain backward compatibility while still enforcing the integer requirement.
+
+## 3. rSpectral - Modularity Calculation Changes
+
+### Issue
+Test failures showing modularity values have changed:
+- Expected: 0.408, Actual: 0.432 (difference: +0.024)
+- Expected: 0.3776, Actual: 0.3758 (difference: -0.0018)
+
+### Root Cause
+From NEWS.md:
+```
+# igraph 2.2.1.9004
+- Use `"weights"` edge attribute in `modularity()` if available.
+```
+
+The `modularity_impl()` function in `R/aaa-auto.R` now has this code:
+
+```r
+if (is.null(weights) && "weight" %in% edge_attr_names(graph)) {
+  weights <- E(graph)$weight
+}
+```
+
+This means that:
+1. If the graph has a "weight" edge attribute, it will be automatically used for modularity calculations
+2. Even if you explicitly pass `weights = NULL`, the function will still use the graph's weight attribute
+3. There is no way to disable weights if the graph has a weight attribute
+
+Previously, `weights = NULL` meant "don't use weights", but now it means "use default weights if available".
+
+Additionally, there's a note in the test output:
+```
+This graph was created by an old(er) igraph version.
+i Call `igraph::upgrade_graph()` on it to use with the current igraph version.
+For now we convert it on the fly...
+```
+
+This suggests the test is using pre-existing graph objects that may have been created with an older version of igraph, and those graphs may have inadvertently gained or lost weight attributes during the upgrade process.
+
+### Assessment
+**This is an inadvertent breaking change in igraph, but a workaround exists.**
+
+The automatic use of weights in modularity calculations is a behavior change that:
+1. Affects existing code that doesn't expect weights to be used
+2. Cannot be overridden by passing `weights = NULL` (which intuitively should mean "don't use weights")
+3. Makes the behavior dependent on whether the graph happens to have a "weight" attribute
+
+The modularity differences are small but significant for tests that check exact values.
+
+**However**, passing `weights = numeric()` provides a simple workaround to force unweighted calculations.
+
+### Workaround
+**A workaround exists**: Passing `weights = numeric()` (an empty numeric vector) effectively disables auto-detection and forces unweighted modularity calculation.
+
+```r
+# With weight attribute, but want unweighted modularity
+E(g)$weight <- runif(ecount(g))
+modularity(g, membership, weights = numeric())  # Unweighted result
+```
+
+This works because:
+1. `numeric()` is not `NULL`, so auto-detection is skipped
+2. The condition `!all(is.na(numeric()))` is `FALSE` (since `all()` of empty vector returns `TRUE`)
+3. This causes the code to set `weights <- NULL` internally
+
+### Recommendation
+**For rSpectral** (and other affected packages):
+1. Update saved graph objects using `upgrade_graph()`
+2. Review whether graphs should have weights or not
+3. If unweighted modularity is needed despite weight attribute, use `weights = numeric()`
+4. Alternatively, remove unintended weights: `g <- delete_edge_attr(g, "weight")`
+5. Update expected test values if the new weighted behavior is correct
+
+**For igraph maintainers** (design decision):
+- **Option 1**: Document `weights = numeric()` as the official way to disable auto-detection
+- **Option 2**: Change logic so `weights = NULL` explicitly disables auto-detection (requires distinguishing missing argument from explicit `NULL`)
+- **Option 3**: Revert to old behavior (no auto-detection, require explicit `weights = E(graph)$weight`)
+
+## Conclusion
+
+| Package | Issue Type | Root Cause | Recommendation |
+|---------|-----------|------------|----------------|
+| Cascade | Namespace collision | New `circulant()` export | Consider unexported constructor or document as known issue |
+| jewel | Integer validation | Stricter type checking in C code | Add `as.integer()` conversion in igraph for backward compatibility |
+| rSpectral | Modularity changes | Automatic weight usage that cannot be overridden with `weights = NULL` | Use `weights = numeric()` workaround, or remove weight attributes |
+
+**Overall Assessment**: 
+- **1 inadvertent behavior change** (Cascade - namespace collision with minor impact)
+- **1 uncovered downstream bug** (jewel - should use integer niter, but igraph could be more forgiving)
+- **1 breaking change** (rSpectral - automatic weights in modularity that cannot be disabled)
+
+### Detailed Recommendations
+
+#### For Cascade (Namespace Collision)
+- **Impact**: Minor - just a warning, doesn't prevent package from working
+- **igraph action**: Consider not exporting the `circulant` constructor alias, only export `make_circulant()`
+- **Package action**: Cascade can add explicit import: `importFrom(magic, circulant)` in NAMESPACE
+
+#### For jewel (Integer Validation)
+- **Impact**: High - package completely breaks
+- **igraph action**: Add backward compatibility by converting to integer in `rewire_keeping_degseq()`:
+  ```r
+  rewire_keeping_degseq <- function(graph, loops, niter) {
+    loops <- as.logical(loops)
+    niter <- as.integer(round(niter))  # Round and convert to integer
+    mode <- if (loops) "simple_loops" else "simple"
+    rewire_impl(rewire = graph, n = niter, mode = mode)
+  }
+  ```
+- **Package action**: jewel should fix their code to use `ceiling(p * 0.05)` instead of `p * 0.05`
+
+#### For rSpectral (Modularity Changes)  
+- **Impact**: Medium - tests fail but core functionality may still work
+- **Workaround available**: Use `weights = numeric()` to disable auto-detection
+- **Package action**: 
+  1. Update saved graphs with `upgrade_graph()`
+  2. Check for unintended weight attributes
+  3. Use `modularity(g, membership, weights = numeric())` for unweighted calculation
+  4. Or remove weights: `g <- delete_edge_attr(g, "weight")`
+  5. Update test expectations if weighted behavior is correct