diff --git a/AGENTS.md b/AGENTS.md
index 443730b..04ae98f 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -175,7 +175,7 @@ The real implementation calls GitHub's REST API. Tests use a mock implementation
 At minimum, every rule must have:
 - A passing case (repo satisfies the rule)
 - A failing case (repo violates the rule)
-- An edge case where applicable (e.g., README exists but is under 100 lines)
+- An edge case where applicable (e.g., README exists but is under 2KB)
 
 Report generation tests must verify the Markdown output matches expected structure.
 
diff --git a/README.md b/README.md
index 02e3306..5fa1097 100644
--- a/README.md
+++ b/README.md
@@ -38,12 +38,12 @@ Each rule produces a **pass** or **fail** result per repository. There are no sc
 **Pass:** file found.
 **Fail:** file not found.
 
-#### 3. Has README over 100 lines
+#### 3. Has README over 2KB
 
-**Check:** a `README.md` file exists in the repo root and contains more than 100 lines.
+**Check:** a `README.md` file exists in the repo root and is larger than 2048 bytes.
 
-**Pass:** `README.md` exists and has >100 lines.
-**Fail:** `README.md` is missing, or exists but has ≤100 lines.
+**Pass:** `README.md` exists and is >2048 bytes.
+**Fail:** `README.md` is missing, or exists but is ≤2048 bytes.
 
 #### 4. Has LICENSE
 
@@ -134,7 +134,7 @@ The report is a single Markdown document posted as a GitHub Issue. Structure:
 |------|--------|
 | Has repo description | ✅ |
 | Has .gitignore | ✅ |
-| Has README over 100 lines | ❌ |
+| Has README over 2KB | ❌ |
 | ... | ... |
 
 ### repo-name-2
diff --git a/client.go b/client.go
index 0fece2f..e7ee424 100644
--- a/client.go
+++ b/client.go
@@ -8,20 +8,26 @@ import (
 	"net/http"
 )
 
+// FileEntry represents a file or directory in a repo's root.
+type FileEntry struct {
+	Name string
+	Size int
+}
+
 // Repo represents a GitHub repository with the fields the scanner needs.
 type Repo struct {
 	Name          string
 	Description   string
 	DefaultBranch string
 	Archived      bool
-	Files         []string // root-level file and directory names
+	Files         []FileEntry // root-level file and directory entries
 }
 
 // GitHubClient is the interface for all GitHub API interactions.
 // The scanner depends only on this interface, making it testable via mocks.
 type GitHubClient interface {
 	ListRepos(ctx context.Context, org string) ([]Repo, error)
-	ListFiles(ctx context.Context, owner, repo string) ([]string, error)
+	ListFiles(ctx context.Context, owner, repo string) ([]FileEntry, error)
 	CreateIssue(ctx context.Context, owner, repo, title, body string) error
 }
 
@@ -102,21 +108,22 @@ func (c *realGitHubClient) ListRepos(ctx context.Context, org string) ([]Repo, e
 	return allRepos, nil
 }
 
-func (c *realGitHubClient) ListFiles(ctx context.Context, owner, repo string) ([]string, error) {
+func (c *realGitHubClient) ListFiles(ctx context.Context, owner, repo string) ([]FileEntry, error) {
 	url := fmt.Sprintf("https://api.github.com/repos/%s/%s/contents", owner, repo)
 
 	var entries []struct {
 		Name string `json:"name"`
+		Size int    `json:"size"`
 	}
 	if err := c.doRequest(ctx, url, &entries); err != nil {
 		return nil, fmt.Errorf("list files for %s/%s: %w", owner, repo, err)
 	}
 
-	names := make([]string, len(entries))
+	files := make([]FileEntry, len(entries))
 	for i, e := range entries {
-		names[i] = e.Name
+		files[i] = FileEntry{Name: e.Name, Size: e.Size}
 	}
-	return names, nil
+	return files, nil
 }
 
 func (c *realGitHubClient) CreateIssue(ctx context.Context, owner, repo, title, body string) error {
diff --git a/client_mock_test.go b/client_mock_test.go
index 93a98ea..7a17cb4 100644
--- a/client_mock_test.go
+++ b/client_mock_test.go
@@ -6,7 +6,7 @@ import "context"
 type MockGitHubClient struct {
 	Repos    []Repo
 	Err      error
-	Files    map[string][]string // repo name -> file list
+	Files    map[string][]FileEntry // repo name -> file entries
 	FilesErr error
 	IssueErr error
 	// CreatedIssue records the last CreateIssue call for assertions.
@@ -19,7 +19,7 @@ func (m *MockGitHubClient) ListRepos(ctx context.Context, org string) ([]Repo, e
 	return m.Repos, m.Err
 }
 
-func (m *MockGitHubClient) ListFiles(ctx context.Context, owner, repo string) ([]string, error) {
+func (m *MockGitHubClient) ListFiles(ctx context.Context, owner, repo string) ([]FileEntry, error) {
 	if m.FilesErr != nil {
 		return nil, m.FilesErr
 	}
diff --git a/rules.go b/rules.go
index 09fe4ba..61347d5 100644
--- a/rules.go
+++ b/rules.go
@@ -19,6 +19,7 @@ func AllRules() []Rule {
 	return []Rule{
 		HasRepoDescription{},
 		HasGitignore{},
+		HasSubstantialReadme{},
 	}
 }
 
@@ -38,11 +39,25 @@ func (r HasGitignore) Check(repo Repo) bool {
 	return hasFile(repo.Files, ".gitignore")
 }
 
-func hasFile(files []string, name string) bool {
+// HasSubstantialReadme checks that README.md exists and is larger than 2048 bytes.
+type HasSubstantialReadme struct{}
+
+func (r HasSubstantialReadme) Name() string { return "Has README over 2KB" }
+func (r HasSubstantialReadme) Check(repo Repo) bool {
+	f, ok := findFile(repo.Files, "README.md")
+	return ok && f.Size > 2048
+}
+
+func findFile(files []FileEntry, name string) (FileEntry, bool) {
 	for _, f := range files {
-		if f == name {
-			return true
+		if f.Name == name {
+			return f, true
 		}
 	}
-	return false
+	return FileEntry{}, false
+}
+
+func hasFile(files []FileEntry, name string) bool {
+	_, ok := findFile(files, name)
+	return ok
 }
diff --git a/rules_test.go b/rules_test.go
index c256265..0f27679 100644
--- a/rules_test.go
+++ b/rules_test.go
@@ -29,7 +29,7 @@ func TestHasRepoDescription_Fail_WhitespaceOnly(t *testing.T) {
 func TestHasGitignore_Pass(t *testing.T) {
 	rule := HasGitignore{}
 
-	if !rule.Check(Repo{Files: []string{"README.md", ".gitignore", "main.go"}}) {
+	if !rule.Check(Repo{Files: []FileEntry{{Name: "README.md"}, {Name: ".gitignore"}, {Name: "main.go"}}}) {
 		t.Error("expected pass when .gitignore exists")
 	}
 }
@@ -37,7 +37,7 @@ func TestHasGitignore_Pass(t *testing.T) {
 func TestHasGitignore_Fail(t *testing.T) {
 	rule := HasGitignore{}
 
-	if rule.Check(Repo{Files: []string{"README.md", "main.go"}}) {
+	if rule.Check(Repo{Files: []FileEntry{{Name: "README.md"}, {Name: "main.go"}}}) {
 		t.Error("expected fail when .gitignore is missing")
 	}
 }
@@ -49,3 +49,27 @@ func TestHasGitignore_Fail_EmptyFiles(t *testing.T) {
 		t.Error("expected fail when file list is empty")
 	}
 }
+
+func TestHasSubstantialReadme_Pass(t *testing.T) {
+	rule := HasSubstantialReadme{}
+
+	if !rule.Check(Repo{Files: []FileEntry{{Name: "README.md", Size: 3000}}}) {
+		t.Error("expected pass for README.md over 2KB")
+	}
+}
+
+func TestHasSubstantialReadme_Fail_TooSmall(t *testing.T) {
+	rule := HasSubstantialReadme{}
+
+	if rule.Check(Repo{Files: []FileEntry{{Name: "README.md", Size: 2048}}}) {
+		t.Error("expected fail for README.md exactly 2048 bytes")
+	}
+}
+
+func TestHasSubstantialReadme_Fail_Missing(t *testing.T) {
+	rule := HasSubstantialReadme{}
+
+	if rule.Check(Repo{Files: []FileEntry{{Name: "main.go"}}}) {
+		t.Error("expected fail when README.md is missing")
+	}
+}