diff --git a/.github/actions/slinky/Dockerfile b/.github/actions/slinky/Dockerfile
new file mode 100644
index 0000000..b1bb0a8
--- /dev/null
+++ b/.github/actions/slinky/Dockerfile
@@ -0,0 +1,19 @@
+FROM golang:1.24 as build
+WORKDIR /app
+# Expect the repository root as build context when building this image
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+RUN CGO_ENABLED=0 go build -o /usr/local/bin/slinky ./
+
+FROM alpine:3.20
+RUN adduser -D -u 10001 appuser \
+    && apk add --no-cache curl jq ca-certificates
+COPY --from=build /usr/local/bin/slinky /usr/local/bin/slinky
+COPY .github/actions/slinky/entrypoint.sh /entrypoint.sh
+RUN chmod +x /entrypoint.sh
+USER appuser
+ENTRYPOINT ["/entrypoint.sh"]
+
+
+
diff --git a/.github/actions/slinky/action.yml b/.github/actions/slinky/action.yml
new file mode 100644
index 0000000..a3a263e
--- /dev/null
+++ b/.github/actions/slinky/action.yml
@@ -0,0 +1,72 @@
+name: "Slinky Link Checker"
+description: "Slink through your repository looking for dead links"
+author: "LukeHagar"
+branding:
+  icon: "link"
+  color: "blue"
+
+inputs:
+  path:
+    description: "Root path to scan"
+    required: false
+    default: "."
+  patterns:
+    description: "Comma-separated doublestar patterns. Ex: docs/**/*.md,**/*.go; default **/*"
+    required: false
+    default: "**/*"
+  concurrency:
+    description: "Maximum concurrent requests"
+    required: false
+    default: "16"
+  timeout:
+    description: "HTTP timeout seconds"
+    required: false
+    default: "10"
+  json-out:
+    description: "Optional path to write JSON results"
+    required: false
+    default: "results.json"
+  md-out:
+    description: "Optional path to write Markdown report for PR comment"
+    required: false
+    default: "results.md"
+  repo-blob-base:
+    description: "Override GitHub blob base URL (https://github.com/<owner>/<repo>/blob/<sha>)"
+    required: false
+    default: ""
+  fail-on-failures:
+    description: "Fail the job if any links fail"
+    required: false
+    default: "true"
+  comment-pr:
+    description: "If running on a PR, post a comment with the report"
+    required: false
+    default: "true"
+  step-summary:
+    description: "Append the report to the GitHub Step Summary"
+    required: false
+    default: "true"
+
+runs:
+  using: "docker"
+  image: "Dockerfile"
+  args: []
+  env:
+    INPUT_PATH: ${{ inputs.path }}
+    INPUT_PATTERNS: ${{ inputs.patterns }}
+    INPUT_CONCURRENCY: ${{ inputs.concurrency }}
+    INPUT_TIMEOUT: ${{ inputs.timeout }}
+    INPUT_JSON_OUT: ${{ inputs["json-out"] }}
+    INPUT_MD_OUT: ${{ inputs["md-out"] }}
+    INPUT_REPO_BLOB_BASE: ${{ inputs["repo-blob-base"] }}
+    INPUT_FAIL_ON_FAILURES: ${{ inputs["fail-on-failures"] }}
+    INPUT_COMMENT_PR: ${{ inputs["comment-pr"] }}
+    INPUT_STEP_SUMMARY: ${{ inputs["step-summary"] }}
+
+outputs:
+  json-path:
+    description: "Path to JSON results file"
+  md-path:
+    description: "Path to Markdown report file"
+
+
diff --git a/.github/actions/slinky/entrypoint.sh b/.github/actions/slinky/entrypoint.sh
new file mode 100644
index 0000000..6058e06
--- /dev/null
+++ b/.github/actions/slinky/entrypoint.sh
@@ -0,0 +1,91 @@
+#!/bin/sh
+set -eu
+
+PATH_ARG="${INPUT_PATH:-.}"
+PATTERNS_ARG="${INPUT_PATTERNS:-**/*}"
+CONCURRENCY_ARG="${INPUT_CONCURRENCY:-16}"
+TIMEOUT_ARG="${INPUT_TIMEOUT:-10}"
+JSON_OUT_ARG="${INPUT_JSON_OUT:-results.json}"
+MD_OUT_ARG="${INPUT_MD_OUT:-results.md}"
+REPO_BLOB_BASE_ARG="${INPUT_REPO_BLOB_BASE:-}"
+FAIL_ON_FAILURES_ARG="${INPUT_FAIL_ON_FAILURES:-true}"
+COMMENT_PR_ARG="${INPUT_COMMENT_PR:-true}"
+STEP_SUMMARY_ARG="${INPUT_STEP_SUMMARY:-true}"
+
+ARGS="check \"${PATH_ARG}\" --concurrency ${CONCURRENCY_ARG} --timeout ${TIMEOUT_ARG}"
+if [ "${FAIL_ON_FAILURES_ARG}" = "true" ]; then
+  ARGS="$ARGS --fail-on-failures true"
+else
+  ARGS="$ARGS --fail-on-failures false"
+fi
+if [ -n "${PATTERNS_ARG}" ]; then
+  # normalize by removing spaces around commas
+  NORM_PATTERNS=$(printf "%s" "${PATTERNS_ARG}" | sed 's/,\s*/,/g')
+  IFS=','
+  set -- $NORM_PATTERNS
+  unset IFS
+  for pat in "$@"; do
+    ARGS="$ARGS --patterns \"$pat\""
+  done
+fi
+if [ -n "${JSON_OUT_ARG}" ]; then
+  ARGS="$ARGS --json-out \"${JSON_OUT_ARG}\""
+fi
+if [ -n "${MD_OUT_ARG}" ]; then
+  ARGS="$ARGS --md-out \"${MD_OUT_ARG}\""
+fi
+
+# Compute GitHub blob base URL for file links used in the Markdown report
+if [ -n "${REPO_BLOB_BASE_ARG}" ]; then
+  export SLINKY_REPO_BLOB_BASE_URL="${REPO_BLOB_BASE_ARG}"
+elif [ -n "${GITHUB_REPOSITORY:-}" ]; then
+  COMMIT_SHA="${GITHUB_SHA:-}"
+  if [ -n "${GITHUB_EVENT_PATH:-}" ] && command -v jq >/dev/null 2>&1; then
+    PR_HEAD_SHA="$(jq -r '.pull_request.head.sha // empty' "$GITHUB_EVENT_PATH" || true)"
+    if [ -n "$PR_HEAD_SHA" ]; then
+      COMMIT_SHA="$PR_HEAD_SHA"
+    fi
+  fi
+  if [ -n "$COMMIT_SHA" ]; then
+    export SLINKY_REPO_BLOB_BASE_URL="https://github.com/${GITHUB_REPOSITORY}/blob/${COMMIT_SHA}"
+  fi
+fi
+
+eval slinky ${ARGS}
+
+# Expose outputs
+if [ -n "${GITHUB_OUTPUT:-}" ]; then
+  if [ -n "${JSON_OUT_ARG}" ]; then
+    echo "json-path=${JSON_OUT_ARG}" >> "$GITHUB_OUTPUT"
+  fi
+  if [ -n "${MD_OUT_ARG}" ]; then
+    echo "md-path=${MD_OUT_ARG}" >> "$GITHUB_OUTPUT"
+  fi
+fi
+
+# Append report to job summary if requested
+if [ "${STEP_SUMMARY_ARG}" = "true" ] && [ -n "${GITHUB_STEP_SUMMARY:-}" ] && [ -n "${MD_OUT_ARG}" ] && [ -f "${MD_OUT_ARG}" ]; then
+  cat "${MD_OUT_ARG}" >> "$GITHUB_STEP_SUMMARY"
+fi
+
+# Post PR comment if this is a PR and requested
+if [ "${COMMENT_PR_ARG}" = "true" ] && [ -n "${MD_OUT_ARG}" ] && [ -f "${MD_OUT_ARG}" ]; then
+  PR_NUMBER=""
+  if [ -n "${GITHUB_EVENT_PATH:-}" ] && command -v jq >/dev/null 2>&1; then
+    PR_NUMBER="$(jq -r '.pull_request.number // empty' "$GITHUB_EVENT_PATH" || true)"
+  fi
+  if [ -n "${PR_NUMBER}" ] && [ -n "${GITHUB_REPOSITORY:-}" ] && [ -n "${GITHUB_TOKEN:-}" ]; then
+    BODY_CONTENT="$(cat "${MD_OUT_ARG}")"
+    # Post the comment
+    curl -sS -H "Authorization: Bearer ${GITHUB_TOKEN}" \
+         -H "Accept: application/vnd.github+json" \
+         -H "X-GitHub-Api-Version: 2022-11-28" \
+         -X POST "https://api.github.com/repos/${GITHUB_REPOSITORY}/issues/${PR_NUMBER}/comments" \
+         -d "$(printf '{"body": %s}' "$(jq -Rs . <<EOF
+${BODY_CONTENT}
+EOF
+)" )" >/dev/null || true
+  fi
+fi
+
+
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..ce4a8bd
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,70 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: '1.24.x'
+
+      - name: Cache go build
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cache/go-build
+            ~/go/pkg/mod
+          key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
+          restore-keys: |
+            ${{ runner.os }}-go-
+
+      - name: Build
+        run: go build ./...
+
+      - name: Run unit tests
+        run: go test ./...
+
+  action-self-test:
+    runs-on: ubuntu-latest
+    needs: test
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Build action image
+        run: |
+          docker build -t slinky-action -f .github/actions/slinky/Dockerfile .
+
+      - name: Run action container (expect nonzero if failures)
+        id: run_action
+        run: |
+          set -e
+          docker run --rm -v "$PWD:/repo" -w /repo -e GITHUB_STEP_SUMMARY="/tmp/summary.md" slinky-action sh -lc \
+            'INPUT_PATH=. INPUT_PATTERNS="test files/**" INPUT_CONCURRENCY=8 INPUT_TIMEOUT=5 INPUT_JSON_OUT=results.json INPUT_MD_OUT=results.md INPUT_FAIL_ON_FAILURES=true INPUT_COMMENT_PR=false INPUT_STEP_SUMMARY=true /entrypoint.sh'
+
+      - name: Upload results.json
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: results
+          path: results.json
+      - name: Upload results.md
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: results-md
+          path: results.md
+
+
diff --git a/.github/workflows/example-slinky.yml b/.github/workflows/example-slinky.yml
new file mode 100644
index 0000000..36e5672
--- /dev/null
+++ b/.github/workflows/example-slinky.yml
@@ -0,0 +1,40 @@
+name: Slinky Example
+
+on:
+  pull_request:
+    branches: [ main ]
+  workflow_dispatch: {}
+
+jobs:
+  slinky:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      pull-requests: write
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Run Slinky link checker
+        uses: ./\.github/actions/slinky
+        with:
+          path: .
+          patterns: "**/*"
+          concurrency: "16"
+          timeout: "10"
+          json-out: results.json
+          md-out: results.md
+          fail-on-failures: "true"
+          comment-pr: "true"
+          step-summary: "true"
+
+      - name: Upload results
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: slinky-results
+          path: |
+            results.json
+            results.md
+
+
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..7f15d1d
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,33 @@
+GO ?= go
+PKG := ./...
+BIN_DIR ?= bin
+BINARY ?= slinky
+BIN := $(BIN_DIR)/$(BINARY)
+
+.PHONY: build test clean check action-image action-run
+
+build: $(BIN)
+
+$(BIN):
+	@mkdir -p $(BIN_DIR)
+	CGO_ENABLED=0 $(GO) build -o $(BIN) ./
+
+test:
+	$(GO) test -v $(PKG)
+
+# Convenience: run the headless check against local test files
+check: build
+	./$(BIN) check . --glob "test files/**" --json-out results.json --fail-on-failures true
+
+# Build the Docker-based GitHub Action locally
+action-image:
+	docker build -t slinky-action -f .github/actions/slinky/Dockerfile .
+
+# Run the Action container against the current repo
+action-run: action-image
+	docker run --rm -v "$(PWD):/repo" -w /repo -e GITHUB_STEP_SUMMARY="/tmp/summary.md" slinky-action sh -lc 'INPUT_PATH=. INPUT_PATTERNS="test files/**" INPUT_CONCURRENCY=8 INPUT_TIMEOUT=5 INPUT_JSON_OUT=results.json INPUT_MD_OUT=results.md INPUT_FAIL_ON_FAILURES=true INPUT_COMMENT_PR=false INPUT_STEP_SUMMARY=true /entrypoint.sh'
+
+clean:
+	rm -rf $(BIN_DIR) results.json results.md
+
+
diff --git a/cmd/check.go b/cmd/check.go
new file mode 100644
index 0000000..842a9ac
--- /dev/null
+++ b/cmd/check.go
@@ -0,0 +1,165 @@
+package cmd
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/spf13/cobra"
+
+	"slinky/internal/fsurls"
+	"slinky/internal/report"
+	"slinky/internal/web"
+)
+
+// SerializableResult mirrors web.Result but omits the error field for JSON.
+type SerializableResult struct {
+	URL         string   `json:"url"`
+	OK          bool     `json:"ok"`
+	Status      int      `json:"status"`
+	ErrMsg      string   `json:"error"`
+	Method      string   `json:"method"`
+	ContentType string   `json:"contentType"`
+	Sources     []string `json:"sources"`
+}
+
+func init() {
+	checkCmd := &cobra.Command{
+		Use:   "check [path]",
+		Short: "Scan a directory for URLs and validate them (headless)",
+		Args:  cobra.MaximumNArgs(1),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			path := "."
+			if len(args) == 1 {
+				path = args[0]
+			}
+
+			var gl []string
+			if len(patterns) > 0 {
+				gl = append(gl, patterns...)
+			} else if globPat != "" {
+				gl = strings.Split(globPat, ",")
+			} else {
+				gl = []string{"**/*"}
+			}
+
+			timeout := time.Duration(timeoutSeconds) * time.Second
+			cfg := web.Config{MaxConcurrency: maxConcurrency, RequestTimeout: timeout}
+
+			// Collect URLs
+			urlToFiles, err := fsurls.CollectURLs(path, gl)
+			if err != nil {
+				return err
+			}
+			var urls []string
+			for u := range urlToFiles {
+				urls = append(urls, u)
+			}
+			sort.Strings(urls)
+
+			// If no URLs found, exit early
+			if len(urls) == 0 {
+				fmt.Println("No URLs found.")
+				return nil
+			}
+
+			// Run checks
+			startedAt := time.Now()
+			ctx, cancel := context.WithCancel(context.Background())
+			defer cancel()
+			results := make(chan web.Result, 256)
+			web.CheckURLs(ctx, urls, urlToFiles, results, nil, cfg)
+
+			var total, okCount, failCount int
+			var failures []SerializableResult
+			var failedResults []web.Result
+
+			for r := range results {
+				total++
+				if r.OK {
+					okCount++
+				} else {
+					failCount++
+				}
+				if jsonOut != "" && !r.OK {
+					failures = append(failures, SerializableResult{
+						URL:         r.URL,
+						OK:          r.OK,
+						Status:      r.Status,
+						ErrMsg:      r.ErrMsg,
+						Method:      r.Method,
+						ContentType: r.ContentType,
+						Sources:     r.Sources,
+					})
+				}
+				if !r.OK {
+					failedResults = append(failedResults, r)
+				}
+			}
+
+			// Write JSON if requested (failures only)
+			if jsonOut != "" {
+				f, ferr := os.Create(jsonOut)
+				if ferr != nil {
+					return ferr
+				}
+				enc := json.NewEncoder(f)
+				enc.SetIndent("", "  ")
+				if err := enc.Encode(failures); err != nil {
+					_ = f.Close()
+					return err
+				}
+				_ = f.Close()
+			}
+
+			// Optionally write Markdown report for PR comment consumption
+			if mdOut != "" {
+				base := repoBlobBase
+				if strings.TrimSpace(base) == "" {
+					base = os.Getenv("SLINKY_REPO_BLOB_BASE_URL")
+				}
+				summary := report.Summary{
+					RootPath:        path,
+					StartedAt:       startedAt,
+					FinishedAt:      time.Now(),
+					Processed:       total,
+					OK:              okCount,
+					Fail:            failCount,
+					JSONPath:        jsonOut,
+					RepoBlobBaseURL: base,
+				}
+				if _, err := report.WriteMarkdown(mdOut, failedResults, summary); err != nil {
+					return err
+				}
+			}
+
+			fmt.Printf("Checked %d URLs: %d OK, %d failed\n", total, okCount, failCount)
+			if failOnFailures && failCount > 0 {
+				return fmt.Errorf("%d links failed", failCount)
+			}
+			return nil
+		},
+	}
+
+	checkCmd.Flags().StringVar(&globPat, "glob", "", "comma-separated glob patterns for files (doublestar); empty = all files")
+	checkCmd.Flags().StringSliceVar(&patterns, "patterns", nil, "file match patterns (doublestar). Examples: docs/**/*.md,**/*.go; defaults to **/*")
+	checkCmd.Flags().IntVar(&maxConcurrency, "concurrency", 16, "maximum concurrent requests")
+	checkCmd.Flags().StringVar(&jsonOut, "json-out", "", "path to write full JSON results (array)")
+	checkCmd.Flags().StringVar(&mdOut, "md-out", "", "path to write Markdown report for PR comment")
+	checkCmd.Flags().StringVar(&repoBlobBase, "repo-blob-base", "", "override GitHub blob base URL (e.g. https://github.com/owner/repo/blob/<sha>)")
+	checkCmd.Flags().IntVar(&timeoutSeconds, "timeout", 10, "HTTP request timeout in seconds")
+	checkCmd.Flags().BoolVar(&failOnFailures, "fail-on-failures", true, "exit non-zero if any links fail")
+
+	rootCmd.AddCommand(checkCmd)
+}
+
+var (
+	timeoutSeconds int
+	failOnFailures bool
+	patterns       []string
+	repoBlobBase   string
+)
diff --git a/cmd/root.go b/cmd/root.go
new file mode 100644
index 0000000..153bdc9
--- /dev/null
+++ b/cmd/root.go
@@ -0,0 +1,23 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+var rootCmd = &cobra.Command{
+	Use:   "slinky",
+	Short: "Link checker for repos/directories and webpages (TUI)",
+	Long:  "Slinky scans a directory/repo for URLs in files or crawls a URL, then validates links concurrently in a TUI.",
+}
+
+func Execute() {
+	if err := rootCmd.Execute(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}
+
+
diff --git a/cmd/run.go b/cmd/run.go
new file mode 100644
index 0000000..6530c38
--- /dev/null
+++ b/cmd/run.go
@@ -0,0 +1,49 @@
+package cmd
+
+import (
+	"strings"
+
+	"github.com/spf13/cobra"
+
+	"slinky/internal/tui"
+	"slinky/internal/web"
+)
+
+func init() {
+	runCmd := &cobra.Command{
+		Use:   "run [path]",
+		Short: "Scan a directory/repo for URLs in files and validate them (TUI)",
+		Args:  cobra.MaximumNArgs(1),
+		RunE: func(cmd *cobra.Command, args []string) error {
+			path := "."
+			if len(args) == 1 {
+				path = args[0]
+			}
+			cfg := web.Config{MaxConcurrency: maxConcurrency}
+			var gl []string
+			if len(patterns) > 0 {
+				gl = append(gl, patterns...)
+			} else if globPat != "" {
+				gl = strings.Split(globPat, ",")
+			} else {
+				gl = []string{"**/*"}
+			}
+			return tui.Run(path, gl, cfg, jsonOut, mdOut)
+		},
+	}
+
+	runCmd.Flags().StringVar(&globPat, "glob", "", "comma-separated glob patterns for files (doublestar); empty = all files")
+	runCmd.Flags().StringSliceVar(&patterns, "patterns", nil, "file match patterns (doublestar). Examples: docs/**/*.md,**/*.go; defaults to **/*")
+	runCmd.Flags().IntVar(&maxConcurrency, "concurrency", 16, "maximum concurrent requests")
+	runCmd.Flags().StringVar(&jsonOut, "json-out", "", "path to write full JSON results (array)")
+	runCmd.Flags().StringVar(&mdOut, "md-out", "", "path to write Markdown report for PR comment")
+	runCmd.Flags().StringVar(&repoBlobBase, "repo-blob-base", "", "override GitHub blob base URL (e.g. https://github.com/owner/repo/blob/<sha>)")
+	rootCmd.AddCommand(runCmd)
+}
+
+var (
+	maxConcurrency int
+	jsonOut        string
+	globPat        string
+	mdOut          string
+)
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..9e04e0c
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,37 @@
+module slinky
+
+go 1.24.0
+
+toolchain go1.24.7
+
+require (
+	github.com/bmatcuk/doublestar/v4 v4.6.1
+	github.com/charmbracelet/bubbles v0.21.0
+	github.com/charmbracelet/bubbletea v1.3.8
+	github.com/charmbracelet/lipgloss v1.1.0
+	github.com/sabhiram/go-gitignore v0.0.0-20210923224102-525f6e181f06
+	github.com/spf13/cobra v1.10.1
+)
+
+require (
+	github.com/aymanbagabas/go-osc52/v2 v2.0.1 // indirect
+	github.com/charmbracelet/colorprofile v0.2.3-0.20250311203215-f60798e515dc // indirect
+	github.com/charmbracelet/harmonica v0.2.0 // indirect
+	github.com/charmbracelet/x/ansi v0.10.1 // indirect
+	github.com/charmbracelet/x/cellbuf v0.0.13-0.20250311204145-2c3ea96c31dd // indirect
+	github.com/charmbracelet/x/term v0.2.1 // indirect
+	github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f // indirect
+	github.com/inconshreveable/mousetrap v1.1.0 // indirect
+	github.com/lucasb-eyer/go-colorful v1.2.0 // indirect
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/mattn/go-localereader v0.0.1 // indirect
+	github.com/mattn/go-runewidth v0.0.16 // indirect
+	github.com/muesli/ansi v0.0.0-20230316100256-276c6243b2f6 // indirect
+	github.com/muesli/cancelreader v0.2.2 // indirect
+	github.com/muesli/termenv v0.16.0 // indirect
+	github.com/rivo/uniseg v0.4.7 // indirect
+	github.com/spf13/pflag v1.0.9 // indirect
+	github.com/xo/terminfo v0.0.0-20220910002029-abceb7e1c41e // indirect
+	golang.org/x/sys v0.36.0 // indirect
+	golang.org/x/text v0.24.0 // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..6f3f02a
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,70 @@
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+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
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diff --git a/internal/fsurls/fsurls.go b/internal/fsurls/fsurls.go
new file mode 100644
index 0000000..79bdef3
--- /dev/null
+++ b/internal/fsurls/fsurls.go
@@ -0,0 +1,287 @@
+package fsurls
+
+import (
+	"bufio"
+	"io"
+	"net/url"
+	"os"
+	"path/filepath"
+	"regexp"
+	"sort"
+	"strings"
+
+	"github.com/bmatcuk/doublestar/v4"
+	ignore "github.com/sabhiram/go-gitignore"
+)
+
+// URL patterns from various contexts
+var bareURLRegex = regexp.MustCompile(`(?i)\bhttps?://[^\s<>()\[\]{}"']+`)
+var mdLinkRegex = regexp.MustCompile(`(?is)!?\[[^\]]*\]\((.*?)\)`) // captures (url)
+var angleURLRegex = regexp.MustCompile(`(?i)<(https?://[^>\s]+)>`)
+var quotedURLRegex = regexp.MustCompile(`(?i)"(https?://[^"\s]+)"|'(https?://[^'\s]+)'`)
+var htmlHrefRegex = regexp.MustCompile(`(?i)href\s*=\s*"([^"]+)"|href\s*=\s*'([^']+)'`)
+var htmlSrcRegex = regexp.MustCompile(`(?i)src\s*=\s*"([^"]+)"|src\s*=\s*'([^']+)'`)
+
+// Strict hostname validation: labels 1-63 chars, alnum & hyphen, not start/end hyphen, at least one dot, simple TLD
+var hostnameRegex = regexp.MustCompile(`^(?i)([a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?)(?:\.[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?)+$`)
+
+// CollectURLs walks the directory tree rooted at rootPath and collects URLs found in
+// text-based files matching any of the provided glob patterns (doublestar ** supported).
+// If globs is empty, all files are considered. Respects .gitignore if present.
+// Returns a map from URL -> sorted unique list of file paths that contained it.
+func CollectURLs(rootPath string, globs []string) (map[string][]string, error) {
+	if strings.TrimSpace(rootPath) == "" {
+		rootPath = "."
+	}
+	cleanRoot := filepath.Clean(rootPath)
+
+	st, _ := os.Stat(cleanRoot)
+	isFileRoot := st != nil && !st.IsDir()
+	var ign *ignore.GitIgnore
+	if !isFileRoot {
+		ign = loadGitIgnore(cleanRoot)
+	}
+
+	var patterns []string
+	for _, g := range globs {
+		g = strings.TrimSpace(g)
+		if g == "" {
+			continue
+		}
+		patterns = append(patterns, g)
+	}
+
+	shouldInclude := func(rel string) bool {
+		if len(patterns) == 0 {
+			return true
+		}
+		for _, p := range patterns {
+			ok, _ := doublestar.PathMatch(p, rel)
+			if ok {
+				return true
+			}
+		}
+		return false
+	}
+
+	urlToFiles := make(map[string]map[string]struct{})
+
+	// 2 MiB max file size to avoid huge/binary files
+	const maxSize = 2 * 1024 * 1024
+
+	// Walk the filesystem
+	walkFn := func(path string, d os.DirEntry, err error) error {
+		if err != nil {
+			return nil
+		}
+		rel, rerr := filepath.Rel(cleanRoot, path)
+		if rerr != nil {
+			rel = path
+		}
+		rel = filepath.ToSlash(rel)
+		if d.IsDir() {
+			base := filepath.Base(path)
+			if base == ".git" {
+				return filepath.SkipDir
+			}
+			if ign != nil && ign.MatchesPath(rel) {
+				return filepath.SkipDir
+			}
+			return nil
+		}
+		if ign != nil && ign.MatchesPath(rel) {
+			return nil
+		}
+		info, ierr := d.Info()
+		if ierr != nil {
+			return nil
+		}
+		if info.Size() > maxSize {
+			return nil
+		}
+		if isFileRoot && rel == "." {
+			rel = filepath.ToSlash(filepath.Base(path))
+		}
+		if !shouldInclude(rel) {
+			return nil
+		}
+
+		f, ferr := os.Open(path)
+		if ferr != nil {
+			return nil
+		}
+		defer f.Close()
+		br := bufio.NewReader(f)
+		// Read up to maxSize bytes
+		var b strings.Builder
+		read := int64(0)
+		for {
+			chunk, cerr := br.ReadString('\n')
+			b.WriteString(chunk)
+			read += int64(len(chunk))
+			if cerr == io.EOF || read > maxSize {
+				break
+			}
+			if cerr != nil {
+				break
+			}
+		}
+		content := b.String()
+		// Skip if likely binary (NUL present)
+		if strings.IndexByte(content, '\x00') >= 0 {
+			return nil
+		}
+
+		candidates := extractCandidates(content)
+		if len(candidates) == 0 {
+			return nil
+		}
+		for _, raw := range candidates {
+			u := sanitizeURLToken(raw)
+			if u == "" {
+				continue
+			}
+			fileSet, ok := urlToFiles[u]
+			if !ok {
+				fileSet = make(map[string]struct{})
+				urlToFiles[u] = fileSet
+			}
+			fileSet[rel] = struct{}{}
+		}
+		return nil
+	}
+
+	_ = filepath.WalkDir(cleanRoot, walkFn)
+
+	// Convert to sorted slices
+	result := make(map[string][]string, len(urlToFiles))
+	for u, files := range urlToFiles {
+		var list []string
+		for fp := range files {
+			list = append(list, fp)
+		}
+		sort.Strings(list)
+		result[u] = list
+	}
+	return result, nil
+}
+
+func sanitizeURLToken(s string) string {
+	s = strings.TrimSpace(s)
+	// Strip surrounding angle brackets or quotes
+	if strings.HasPrefix(s, "<") && strings.HasSuffix(s, ">") {
+		s = strings.TrimSuffix(strings.TrimPrefix(s, "<"), ">")
+	}
+	if (strings.HasPrefix(s, "\"") && strings.HasSuffix(s, "\"")) || (strings.HasPrefix(s, "'") && strings.HasSuffix(s, "'")) {
+		s = strings.TrimSuffix(strings.TrimPrefix(s, string(s[0])), string(s[0]))
+	}
+	// Trim trailing punctuation and balance parentheses
+	s = trimTrailingDelimiters(s)
+	low := strings.ToLower(s)
+	if !(strings.HasPrefix(low, "http://") || strings.HasPrefix(low, "https://")) {
+		return ""
+	}
+	// Parse and validate hostname strictly
+	u, err := url.Parse(s)
+	if err != nil || u == nil {
+		return ""
+	}
+	host := u.Hostname()
+	if host == "" {
+		return ""
+	}
+	// Reject placeholders like [tenant] or {tenant}
+	if strings.ContainsAny(host, "[]{}") {
+		return ""
+	}
+	// Must match strict hostname rules
+	if !hostnameRegex.MatchString(host) {
+		return ""
+	}
+	return s
+}
+
+func trimTrailingDelimiters(s string) string {
+	for {
+		if s == "" {
+			return s
+		}
+		last := s[len(s)-1]
+		if strings.ContainsRune(").,;:!?]'\"}", rune(last)) {
+			s = s[:len(s)-1]
+			continue
+		}
+		if last == ')' {
+			open := strings.Count(s, "(")
+			close := strings.Count(s, ")")
+			if close > open {
+				s = s[:len(s)-1]
+				continue
+			}
+		}
+		return s
+	}
+}
+
+func extractCandidates(content string) []string {
+	var out []string
+	for _, m := range mdLinkRegex.FindAllStringSubmatch(content, -1) {
+		if len(m) > 1 {
+			out = append(out, m[1])
+		}
+	}
+	for _, m := range htmlHrefRegex.FindAllStringSubmatch(content, -1) {
+		if len(m) > 2 {
+			if m[1] != "" {
+				out = append(out, m[1])
+			} else if m[2] != "" {
+				out = append(out, m[2])
+			}
+		}
+	}
+	for _, m := range htmlSrcRegex.FindAllStringSubmatch(content, -1) {
+		if len(m) > 2 {
+			if m[1] != "" {
+				out = append(out, m[1])
+			} else if m[2] != "" {
+				out = append(out, m[2])
+			}
+		}
+	}
+	for _, m := range angleURLRegex.FindAllStringSubmatch(content, -1) {
+		if len(m) > 1 {
+			out = append(out, m[1])
+		}
+	}
+	for _, m := range quotedURLRegex.FindAllStringSubmatch(content, -1) {
+		if len(m) > 2 {
+			if m[1] != "" {
+				out = append(out, m[1])
+			} else if m[2] != "" {
+				out = append(out, m[2])
+			}
+		}
+	}
+	out = append(out, bareURLRegex.FindAllString(content, -1)...)
+	return out
+}
+
+func loadGitIgnore(root string) *ignore.GitIgnore {
+	var lines []string
+	gi := filepath.Join(root, ".gitignore")
+	if b, err := os.ReadFile(gi); err == nil {
+		for _, ln := range strings.Split(string(b), "\n") {
+			lines = append(lines, ln)
+		}
+	}
+	ge := filepath.Join(root, ".git", "info", "exclude")
+	if b, err := os.ReadFile(ge); err == nil {
+		for _, ln := range strings.Split(string(b), "\n") {
+			lines = append(lines, ln)
+		}
+	}
+	if len(lines) == 0 {
+		return nil
+	}
+	return ignore.CompileIgnoreLines(lines...)
+}
diff --git a/internal/fsurls/fsurls_test.go b/internal/fsurls/fsurls_test.go
new file mode 100644
index 0000000..cf37ded
--- /dev/null
+++ b/internal/fsurls/fsurls_test.go
@@ -0,0 +1,43 @@
+package fsurls
+
+import (
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestCollectURLs_FromTestFiles(t *testing.T) {
+	root := filepath.Join("..", "..", "test files")
+
+	urls, err := CollectURLs(root, []string{"**/*"})
+	if err != nil {
+		t.Fatalf("CollectURLs error: %v", err)
+	}
+
+	// Spot-check presence of some known URLs
+	mustContain := []string{
+		"https://example.com",
+		"https://en.wikipedia.org/wiki/Main_Page",
+		"http://example.com:8080",
+		"http://example..com", // appears in multiple files
+		"https://this-domain-does-not-exist-123456789.com",
+	}
+	for _, u := range mustContain {
+		if _, ok := urls[u]; !ok {
+			// Show nearby URLs to aid debugging if it fails.
+			var sample []string
+			for seen := range urls {
+				if strings.Contains(seen, "example") {
+					sample = append(sample, seen)
+				}
+			}
+			t.Fatalf("expected URL %q to be collected; example URLs seen: %v", u, sample)
+		}
+	}
+
+	// Ensure sources are recorded for a known URL
+	srcs := urls["https://example.com"]
+	if len(srcs) == 0 {
+		t.Fatalf("expected sources for https://example.com, got none")
+	}
+}
diff --git a/internal/fsurls/lang_files_test.go b/internal/fsurls/lang_files_test.go
new file mode 100644
index 0000000..6e1d8c0
--- /dev/null
+++ b/internal/fsurls/lang_files_test.go
@@ -0,0 +1,42 @@
+package fsurls
+
+import (
+	"path/filepath"
+	"testing"
+)
+
+func TestCollectURLs_FromCodeFiles(t *testing.T) {
+	root := filepath.Join("..", "..", "test files")
+	urls, err := CollectURLs(root, []string{"**/*"})
+	if err != nil {
+		t.Fatalf("CollectURLs error: %v", err)
+	}
+
+	// Valid URLs from various languages should be present (including a known nonexistent-but-well-formed)
+	valids := []string{
+		"https://example.com",
+		"https://en.wikipedia.org/wiki/Main_Page",
+		"https://developer.mozilla.org",
+		"https://svelte.dev",
+		"https://go.dev/doc/",
+		"https://this-domain-does-not-exist-123456789.com",
+	}
+	for _, u := range valids {
+		if _, ok := urls[u]; !ok {
+			t.Fatalf("expected valid URL %q to be collected", u)
+		}
+	}
+
+	// Placeholder patterns should be excluded by strict validation
+	placeholders := []string{
+		"https://[tenant].api.identitynow.com",
+		"https://{tenant}.api.identitynow.com",
+		"https://[tenant].[domain].com",
+		"https://{tenant}.api.ideidentitynow.com/v3/transforms",
+	}
+	for _, u := range placeholders {
+		if _, ok := urls[u]; ok {
+			t.Fatalf("did not expect placeholder URL %q to be collected", u)
+		}
+	}
+}
diff --git a/internal/report/markdown.go b/internal/report/markdown.go
new file mode 100644
index 0000000..3250dda
--- /dev/null
+++ b/internal/report/markdown.go
@@ -0,0 +1,168 @@
+package report
+
+import (
+	"bytes"
+	"fmt"
+	"html"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"time"
+
+	"slinky/internal/web"
+)
+
+// Summary captures high-level run details for the report.
+type Summary struct {
+	RootPath        string
+	StartedAt       time.Time
+	FinishedAt      time.Time
+	Processed       int
+	OK              int
+	Fail            int
+	AvgRPS          float64
+	PeakRPS         float64
+	LowRPS          float64
+	JSONPath        string
+	RepoBlobBaseURL string // e.g. https://github.com/owner/repo/blob/<sha>
+}
+
+// WriteMarkdown writes a GitHub-flavored Markdown report to path. If path is empty,
+// it derives a safe filename from s.RootPath.
+func WriteMarkdown(path string, results []web.Result, s Summary) (string, error) {
+	if strings.TrimSpace(path) == "" {
+		base := filepath.Base(s.RootPath)
+		if strings.TrimSpace(base) == "" || base == "." || base == string(filepath.Separator) {
+			base = "results"
+		}
+		var b strings.Builder
+		for _, r := range strings.ToLower(base) {
+			if (r >= 'a' && r <= 'z') || (r >= '0' && r <= '9') || r == '-' || r == '_' || r == '.' {
+				b.WriteRune(r)
+			} else {
+				b.WriteByte('_')
+			}
+		}
+		path = fmt.Sprintf("%s.md", b.String())
+	}
+
+	var buf bytes.Buffer
+	// Title and summary
+	buf.WriteString("## Slinky Test Report\n\n")
+	buf.WriteString(fmt.Sprintf("- **Root**: %s\n", escapeMD(s.RootPath)))
+	buf.WriteString(fmt.Sprintf("- **Started**: %s\n", s.StartedAt.Format("2006-01-02 15:04:05 MST")))
+	buf.WriteString(fmt.Sprintf("- **Finished**: %s\n", s.FinishedAt.Format("2006-01-02 15:04:05 MST")))
+	buf.WriteString(fmt.Sprintf("- **Processed**: %d  •  **OK**: %d  •  **Fail**: %d\n", s.Processed, s.OK, s.Fail))
+	buf.WriteString(fmt.Sprintf("- **Rates**: avg %.1f/s  •  peak %.1f/s  •  low %.1f/s\n", s.AvgRPS, s.PeakRPS, s.LowRPS))
+	if s.JSONPath != "" {
+		base := filepath.Base(s.JSONPath)
+		buf.WriteString(fmt.Sprintf("- **JSON**: %s\n", escapeMD(base)))
+	}
+	buf.WriteString("\n")
+
+	// Failures by URL
+	buf.WriteString("### Failures by URL\n\n")
+
+	// Gather issues per URL with list of files
+	type fileRef struct {
+		Path string
+	}
+	type urlIssue struct {
+		Status int
+		Method string
+		ErrMsg string
+		Files  []fileRef
+	}
+	byURL := make(map[string]*urlIssue)
+	for _, r := range results {
+		ui, ok := byURL[r.URL]
+		if !ok {
+			ui = &urlIssue{Status: r.Status, Method: r.Method, ErrMsg: r.ErrMsg}
+			byURL[r.URL] = ui
+		}
+		for _, src := range r.Sources {
+			ui.Files = append(ui.Files, fileRef{Path: src})
+		}
+	}
+
+	// Sort URLs
+	var urls []string
+	for u := range byURL {
+		urls = append(urls, u)
+	}
+	sort.Strings(urls)
+
+	for _, u := range urls {
+		ui := byURL[u]
+		// Header line for URL
+		if ui.Status > 0 {
+			buf.WriteString(fmt.Sprintf("- %d %s `%s` — %s\n", ui.Status, escapeMD(ui.Method), escapeMD(u), escapeMD(ui.ErrMsg)))
+		} else {
+			buf.WriteString(fmt.Sprintf("- %s `%s` — %s\n", escapeMD(ui.Method), escapeMD(u), escapeMD(ui.ErrMsg)))
+		}
+		// Files list (collapsible)
+		buf.WriteString("  <details><summary>files</summary>\n\n")
+		// Deduplicate and sort file paths
+		seen := make(map[string]struct{})
+		var files []string
+		for _, fr := range ui.Files {
+			if _, ok := seen[fr.Path]; ok {
+				continue
+			}
+			seen[fr.Path] = struct{}{}
+			files = append(files, fr.Path)
+		}
+		sort.Strings(files)
+		for _, fn := range files {
+			if strings.TrimSpace(s.RepoBlobBaseURL) != "" {
+				buf.WriteString(fmt.Sprintf("  - [%s](%s/%s)\n", escapeMD(fn), strings.TrimRight(s.RepoBlobBaseURL, "/"), escapeLinkPath(fn)))
+			} else {
+				buf.WriteString(fmt.Sprintf("  - [%s](./%s)\n", escapeMD(fn), escapeLinkPath(fn)))
+			}
+		}
+		buf.WriteString("\n  </details>\n\n")
+	}
+
+	f, err := os.Create(path)
+	if err != nil {
+		return "", err
+	}
+	defer f.Close()
+	if _, err := f.Write(buf.Bytes()); err != nil {
+		return "", err
+	}
+	return path, nil
+}
+
+func escapeMD(s string) string {
+	// Basic HTML escape to be safe in GitHub Markdown table cells
+	return html.EscapeString(s)
+}
+
+// formatSourcesList renders a list of file paths as an HTML unordered list suitable
+// for inclusion in a Markdown table cell. Individual entries are escaped.
+func formatSourcesList(srcs []string) string {
+	if len(srcs) == 0 {
+		return ""
+	}
+	var b strings.Builder
+	b.WriteString("<ul>\n")
+	for _, s := range srcs {
+		b.WriteString("  <li><code>")
+		b.WriteString(escapeMD(s))
+		b.WriteString("</code></li>\n")
+	}
+	b.WriteString("</ul>")
+	return b.String()
+}
+
+// escapeLinkPath escapes a relative path for inclusion in a Markdown link URL.
+// We keep it simple and only escape parentheses and spaces.
+func escapeLinkPath(p string) string {
+	// Replace spaces with %20 and parentheses with encoded forms
+	p = strings.ReplaceAll(p, " ", "%20")
+	p = strings.ReplaceAll(p, "(", "%28")
+	p = strings.ReplaceAll(p, ")", "%29")
+	return p
+}
diff --git a/internal/tui/fs_bridge.go b/internal/tui/fs_bridge.go
new file mode 100644
index 0000000..861e759
--- /dev/null
+++ b/internal/tui/fs_bridge.go
@@ -0,0 +1,10 @@
+package tui
+
+import (
+	"slinky/internal/fsurls"
+)
+
+// fsCollect is a tiny bridge to avoid importing fsurls directly in tui.go
+func fsCollect(root string, globs []string) (map[string][]string, error) {
+	return fsurls.CollectURLs(root, globs)
+}
diff --git a/internal/tui/tui.go b/internal/tui/tui.go
new file mode 100644
index 0000000..8b35e0c
--- /dev/null
+++ b/internal/tui/tui.go
@@ -0,0 +1,319 @@
+package tui
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"time"
+
+	"github.com/charmbracelet/bubbles/progress"
+	"github.com/charmbracelet/bubbles/spinner"
+	"github.com/charmbracelet/bubbles/viewport"
+	tea "github.com/charmbracelet/bubbletea"
+	"github.com/charmbracelet/lipgloss"
+
+	"slinky/internal/report"
+	"slinky/internal/web"
+)
+
+type linkResultMsg struct{ res web.Result }
+type crawlDoneMsg struct{}
+type statsMsg struct{ s web.Stats }
+type tickMsg struct{ t time.Time }
+
+type model struct {
+	rootPath string
+	cfg      web.Config
+	jsonOut  string
+	mdOut    string
+	globs    []string
+
+	results    chan web.Result
+	stats      chan web.Stats
+	started    time.Time
+	finishedAt time.Time
+	done       bool
+
+	spin spinner.Model
+	prog progress.Model
+	vp   viewport.Model
+
+	lines []string
+
+	total int
+	ok    int
+	fail  int
+
+	pending   int
+	processed int
+
+	lastProcessed int
+	rps           float64
+	peakRPS       float64
+	lowRPS        float64
+
+	allResults []web.Result
+	jsonPath   string
+	mdPath     string
+
+	showFail bool
+}
+
+// Run scans files under rootPath matching globs, extracts URLs, and checks them.
+func Run(rootPath string, globs []string, cfg web.Config, jsonOut string, mdOut string) error {
+	m := &model{rootPath: rootPath, cfg: cfg, jsonOut: jsonOut, mdOut: mdOut, globs: globs}
+	p := tea.NewProgram(m, tea.WithAltScreen())
+	return p.Start()
+}
+
+func (m *model) Init() tea.Cmd {
+	m.spin = spinner.New()
+	m.spin.Spinner = spinner.Dot
+	m.spin.Style = lipgloss.NewStyle().Foreground(lipgloss.Color("205"))
+	m.prog = progress.New(progress.WithDefaultGradient())
+	m.started = time.Now()
+	m.lowRPS = -1
+	m.results = make(chan web.Result, 256)
+	m.stats = make(chan web.Stats, 64)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	go func() {
+		defer cancel()
+		urlsMap, _ := fsCollect(m.rootPath, m.globs)
+		var urls []string
+		for u := range urlsMap {
+			urls = append(urls, u)
+		}
+		web.CheckURLs(ctx, urls, urlsMap, m.results, m.stats, m.cfg)
+	}()
+
+	return tea.Batch(m.spin.Tick, m.waitForEvent(), tickCmd())
+}
+
+func tickCmd() tea.Cmd {
+	return tea.Tick(time.Second, func(t time.Time) tea.Msg { return tickMsg{t: t} })
+}
+
+func (m *model) waitForEvent() tea.Cmd {
+	return func() tea.Msg {
+		if m.results == nil {
+			return crawlDoneMsg{}
+		}
+		select {
+		case res, ok := <-m.results:
+			if ok {
+				return linkResultMsg{res: res}
+			}
+			return crawlDoneMsg{}
+		case s := <-m.stats:
+			return statsMsg{s: s}
+		}
+	}
+}
+
+func (m *model) Update(msg tea.Msg) (tea.Model, tea.Cmd) {
+	switch msg := msg.(type) {
+	case tea.KeyMsg:
+		switch msg.String() {
+		case "q", "ctrl+c":
+			return m, tea.Quit
+		case "f":
+			m.showFail = !m.showFail
+			m.refreshViewport()
+			return m, nil
+		}
+	case tea.WindowSizeMsg:
+		// Reserve space for header (1), stats (1), progress (1), spacer (1), footer (1)
+		reserved := 5
+		if m.vp.Width == 0 {
+			m.vp = viewport.Model{Width: msg.Width, Height: max(msg.Height-reserved, 3)}
+		} else {
+			m.vp.Width = msg.Width
+			m.vp.Height = max(msg.Height-reserved, 3)
+		}
+		m.prog.Width = max(msg.Width-4, 10)
+		m.refreshViewport()
+		return m, nil
+	case linkResultMsg:
+		// Show every event in the log
+		prefix := statusEmoji(msg.res.OK, msg.res.Err)
+		if msg.res.CacheHit {
+			prefix = "🗃"
+		}
+		line := fmt.Sprintf("%s %3d %s", prefix, msg.res.Status, msg.res.URL)
+		m.lines = append(m.lines, line)
+		// Only count non-cache-hit in totals and JSON export
+		if !msg.res.CacheHit {
+			m.total++
+			if msg.res.OK && msg.res.Err == nil {
+				m.ok++
+			} else {
+				m.fail++
+			}
+			m.allResults = append(m.allResults, msg.res)
+		}
+		m.refreshViewport()
+		return m, m.waitForEvent()
+	case statsMsg:
+		m.pending = msg.s.Pending
+		m.processed = msg.s.Processed
+		return m, m.waitForEvent()
+	case tickMsg:
+		// compute requests/sec over the last tick
+		delta := m.processed - m.lastProcessed
+		m.lastProcessed = m.processed
+		m.rps = float64(delta)
+		if m.rps > m.peakRPS {
+			m.peakRPS = m.rps
+		}
+		if m.lowRPS < 0 || m.rps < m.lowRPS {
+			m.lowRPS = m.rps
+		}
+		return m, tickCmd()
+	case crawlDoneMsg:
+		m.done = true
+		m.finishedAt = time.Now()
+		m.results = nil
+		m.writeJSON()
+		m.writeMarkdown()
+		return m, tea.Quit
+	}
+
+	var cmd tea.Cmd
+	m.spin, cmd = m.spin.Update(msg)
+	return m, cmd
+}
+
+func (m *model) refreshViewport() {
+	var filtered []string
+	if m.showFail {
+		for _, l := range m.lines {
+			if strings.HasPrefix(l, "❌") {
+				filtered = append(filtered, l)
+			}
+		}
+	} else {
+		filtered = m.lines
+	}
+	m.vp.SetContent(strings.Join(filtered, "\n"))
+	m.vp.GotoBottom()
+}
+
+func (m *model) writeJSON() {
+	path := m.jsonOut
+	if strings.TrimSpace(path) == "" {
+		base := filepath.Base(m.rootPath)
+		if strings.TrimSpace(base) == "" || base == "." || base == string(filepath.Separator) {
+			base = "results"
+		}
+		re := regexp.MustCompile(`[^a-zA-Z0-9.-]+`)
+		safe := re.ReplaceAllString(strings.ToLower(base), "_")
+		path = fmt.Sprintf("%s.json", safe)
+	}
+	f, err := os.Create(path)
+	if err != nil {
+		return
+	}
+	defer f.Close()
+	// Only write failing results
+	var fails []web.Result
+	for _, r := range m.allResults {
+		if !(r.OK && r.Err == nil) {
+			fails = append(fails, r)
+		}
+	}
+	enc := json.NewEncoder(f)
+	enc.SetIndent("", "  ")
+	_ = enc.Encode(fails)
+	m.jsonPath = path
+}
+
+func (m *model) writeMarkdown() {
+	// Compute average RPS over entire run
+	dur := m.finishedAt.Sub(m.started)
+	avg := 0.0
+	if dur.Seconds() > 0 {
+		avg = float64(m.processed) / dur.Seconds()
+	}
+	s := report.Summary{
+		RootPath:        m.rootPath,
+		StartedAt:       m.started,
+		FinishedAt:      m.finishedAt,
+		Processed:       m.processed,
+		OK:              m.ok,
+		Fail:            m.fail,
+		AvgRPS:          avg,
+		PeakRPS:         m.peakRPS,
+		LowRPS:          m.lowRPS,
+		JSONPath:        m.jsonPath,
+		RepoBlobBaseURL: os.Getenv("SLINKY_REPO_BLOB_BASE_URL"),
+	}
+	// Only include failing results in the markdown report
+	var failsMD []web.Result
+	for _, r := range m.allResults {
+		if !(r.OK && r.Err == nil) {
+			failsMD = append(failsMD, r)
+		}
+	}
+	p, err := report.WriteMarkdown(m.mdOut, failsMD, s)
+	if err == nil {
+		m.mdPath = p
+	}
+}
+
+func (m *model) View() string {
+	header := lipgloss.NewStyle().Bold(true).Render(fmt.Sprintf(" Scanning %s ", m.rootPath))
+	if m.done {
+		dur := time.Since(m.started)
+		if !m.finishedAt.IsZero() {
+			dur = m.finishedAt.Sub(m.started)
+		}
+		avg := 0.0
+		if dur.Seconds() > 0 {
+			avg = float64(m.processed) / dur.Seconds()
+		}
+		summary := []string{
+			fmt.Sprintf("Duration: %s", dur.Truncate(time.Millisecond)),
+			fmt.Sprintf("Processed: %d  OK:%d  Fail:%d", m.processed, m.ok, m.fail),
+			fmt.Sprintf("Rates: avg %.1f/s  peak %.1f/s  low %.1f/s", avg, m.peakRPS, m.lowRPS),
+		}
+		if m.jsonPath != "" {
+			summary = append(summary, fmt.Sprintf("JSON: %s", m.jsonPath))
+		}
+		if m.mdPath != "" {
+			summary = append(summary, fmt.Sprintf("Markdown: %s", m.mdPath))
+		}
+		footer := lipgloss.NewStyle().Faint(true).Render("Controls: [q] quit  [f] toggle fails")
+		container := lipgloss.NewStyle().Padding(1)
+		return container.Render(strings.Join(append([]string{header}, append(summary, footer)...), "\n"))
+	}
+	percent := 0.0
+	totalWork := m.processed + m.pending
+	if totalWork > 0 {
+		percent = float64(m.processed) / float64(totalWork)
+	}
+	progressLine := m.prog.ViewAs(percent)
+	stats := fmt.Sprintf("%s  total:%d  ok:%d  fail:%d  pending:%d processed:%d  rps:%.1f/s", m.spin.View(), m.total, m.ok, m.fail, m.pending, m.processed, m.rps)
+	body := m.vp.View()
+	footer := lipgloss.NewStyle().Faint(true).Render("Controls: [q] quit  [f] toggle fails")
+	container := lipgloss.NewStyle().Padding(1)
+	return container.Render(strings.Join([]string{header, stats, progressLine, "", body, footer}, "\n"))
+}
+
+func statusEmoji(ok bool, err error) string {
+	if ok && err == nil {
+		return "✅"
+	}
+	return "❌"
+}
+
+func max(a, b int) int {
+	if a > b {
+		return a
+	}
+	return b
+}
diff --git a/internal/web/checker.go b/internal/web/checker.go
new file mode 100644
index 0000000..1ec711c
--- /dev/null
+++ b/internal/web/checker.go
@@ -0,0 +1,103 @@
+package web
+
+import (
+	"context"
+	"net"
+	"net/http"
+	"sort"
+	"time"
+)
+
+// CheckURLs performs concurrent GET requests for each URL and emits Result events.
+// sources maps URL -> list of file paths where it was found.
+func CheckURLs(ctx context.Context, urls []string, sources map[string][]string, out chan<- Result, stats chan<- Stats, cfg Config) {
+	defer close(out)
+
+	// Build HTTP client similar to crawler
+	transport := &http.Transport{
+		Proxy:                 http.ProxyFromEnvironment,
+		DialContext:           (&net.Dialer{Timeout: 2 * time.Second, KeepAlive: 30 * time.Second}).DialContext,
+		TLSHandshakeTimeout:   5 * time.Second,
+		ExpectContinueTimeout: 1 * time.Second,
+		MaxIdleConns:          cfg.MaxConcurrency * 2,
+		MaxIdleConnsPerHost:   cfg.MaxConcurrency,
+		MaxConnsPerHost:       cfg.MaxConcurrency,
+		IdleConnTimeout:       30 * time.Second,
+		ResponseHeaderTimeout: cfg.RequestTimeout,
+	}
+	client := &http.Client{Timeout: cfg.RequestTimeout, Transport: transport}
+
+	type job struct{ url string }
+	jobs := make(chan job, len(urls))
+	done := make(chan struct{})
+
+	// Seed jobs
+	unique := make(map[string]struct{}, len(urls))
+	for _, u := range urls {
+		if u == "" {
+			continue
+		}
+		if _, ok := unique[u]; ok {
+			continue
+		}
+		unique[u] = struct{}{}
+		jobs <- job{url: u}
+	}
+	close(jobs)
+
+	concurrency := cfg.MaxConcurrency
+	if concurrency <= 0 {
+		concurrency = 8
+	}
+	processed := 0
+	pending := len(unique)
+
+	worker := func() {
+		for j := range jobs {
+			select {
+			case <-ctx.Done():
+				return
+			default:
+			}
+			ok, status, resp, err := fetchWithMethod(ctx, client, http.MethodGet, j.url)
+			if resp != nil && resp.Body != nil {
+				resp.Body.Close()
+			}
+			// Treat 401/403 as valid links (exist but require authorization)
+			if status == http.StatusUnauthorized || status == http.StatusForbidden {
+				ok = true
+				err = nil
+			}
+			var srcs []string
+			if sources != nil {
+				srcs = sources[j.url]
+			}
+			out <- Result{URL: j.url, OK: ok, Status: status, Err: err, ErrMsg: errString(err), Method: http.MethodGet, Sources: cloneAndSort(srcs)}
+			processed++
+			pending--
+			if stats != nil {
+				select {
+				case stats <- Stats{Pending: pending, Processed: processed}:
+				default:
+				}
+			}
+		}
+		done <- struct{}{}
+	}
+
+	for i := 0; i < concurrency; i++ {
+		go worker()
+	}
+	for i := 0; i < concurrency; i++ {
+		<-done
+	}
+}
+
+func cloneAndSort(in []string) []string {
+	if len(in) == 0 {
+		return nil
+	}
+	out := append([]string(nil), in...)
+	sort.Strings(out)
+	return out
+}
diff --git a/internal/web/checker_test.go b/internal/web/checker_test.go
new file mode 100644
index 0000000..b645c66
--- /dev/null
+++ b/internal/web/checker_test.go
@@ -0,0 +1,53 @@
+package web
+
+import (
+	"context"
+	"testing"
+	"time"
+)
+
+// This test exercises CheckURLs with a mix of known-good and invalid URLs.
+// It does real network calls; keep timeouts short to avoid long CI runs.
+func TestCheckURLs_Basic(t *testing.T) {
+	urls := []string{
+		"https://example.com",                              // should be OK
+		"https://en.wikipedia.org/wiki/Main_Page",          // should be OK
+		"http://example..com",                              // invalid hostname
+		"https://this-domain-does-not-exist-123456789.com", // NXDOMAIN/nonexistent
+	}
+
+	sources := map[string][]string{
+		"https://example.com":                              {"test files/test2.txt"},
+		"https://en.wikipedia.org/wiki/Main_Page":          {"test files/test5.html"},
+		"http://example..com":                              {"test files/test5.html"},
+		"https://this-domain-does-not-exist-123456789.com": {"test files/test5.html"},
+	}
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	out := make(chan Result, 16)
+	cfg := Config{MaxConcurrency: 8, RequestTimeout: 5 * time.Second}
+
+	go CheckURLs(ctx, urls, sources, out, nil, cfg)
+
+	seen := 0
+	var okCount, failCount int
+	for r := range out {
+		seen++
+		if r.OK {
+			okCount++
+		} else {
+			failCount++
+		}
+	}
+
+	if seen != len(urls) {
+		t.Fatalf("expected %d results, got %d", len(urls), seen)
+	}
+	if okCount == 0 {
+		t.Fatalf("expected at least one OK result")
+	}
+	if failCount == 0 {
+		t.Fatalf("expected at least one failure result")
+	}
+}
diff --git a/internal/web/http.go b/internal/web/http.go
new file mode 100644
index 0000000..e020a0b
--- /dev/null
+++ b/internal/web/http.go
@@ -0,0 +1,68 @@
+package web
+
+import (
+	"context"
+	"errors"
+	"net"
+	"net/http"
+	"strings"
+)
+
+const browserUA = "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/123.0 Safari/537.36"
+
+func fetchWithMethod(ctx context.Context, client *http.Client, method string, raw string) (bool, int, *http.Response, error) {
+	req, err := http.NewRequestWithContext(ctx, method, raw, nil)
+	if err != nil {
+		return false, 0, nil, err
+	}
+	req.Header.Set("User-Agent", browserUA)
+	req.Header.Set("Accept", "*/*")
+	resp, err := client.Do(req)
+	if err != nil {
+		if isDNSError(err) {
+			return false, 404, nil, simpleError("host not found")
+		}
+		if isTimeout(err) {
+			return false, 408, nil, simpleError("request timeout")
+		}
+		if isRefused(err) {
+			return false, 503, nil, simpleError("connection refused")
+		}
+		return false, 0, nil, err
+	}
+	return resp.StatusCode >= 200 && resp.StatusCode < 400, resp.StatusCode, resp, nil
+}
+
+func errString(e error) string {
+	if e == nil {
+		return ""
+	}
+	return e.Error()
+}
+
+func isTimeout(err error) bool {
+	if err == nil {
+		return false
+	}
+	if errors.Is(err, context.DeadlineExceeded) {
+		return true
+	}
+	if ne, ok := err.(net.Error); ok && ne.Timeout() {
+		return true
+	}
+	return false
+}
+
+func isDNSError(err error) bool {
+	msg := strings.ToLower(err.Error())
+	return strings.Contains(msg, "no such host") || strings.Contains(msg, "server misbehaving")
+}
+
+func isRefused(err error) bool {
+	msg := strings.ToLower(err.Error())
+	return strings.Contains(msg, "connection refused")
+}
+
+type simpleError string
+
+func (e simpleError) Error() string { return string(e) }
diff --git a/internal/web/types.go b/internal/web/types.go
new file mode 100644
index 0000000..f5bbdc1
--- /dev/null
+++ b/internal/web/types.go
@@ -0,0 +1,29 @@
+package web
+
+import "time"
+
+type Result struct {
+	URL         string
+	OK          bool
+	Status      int
+	Err         error
+	ErrMsg      string
+	Depth       int
+	CacheHit    bool
+	Method      string
+	ContentType string
+	Sources     []string
+}
+
+type Stats struct {
+	Pending   int
+	Processed int
+}
+
+type Config struct {
+	MaxDepth       int
+	MaxConcurrency int
+	RequestTimeout time.Duration
+	MaxRetries429  int
+	Exclude        []string
+}
diff --git a/main.go b/main.go
new file mode 100644
index 0000000..6d4c0e4
--- /dev/null
+++ b/main.go
@@ -0,0 +1,9 @@
+package main
+
+import "slinky/cmd"
+
+func main() {
+	cmd.Execute()
+}
+
+
diff --git a/test files/test nesting/test more nesting/test1.md b/test files/test nesting/test more nesting/test1.md
new file mode 100644
index 0000000..df0df1e
--- /dev/null
+++ b/test files/test nesting/test more nesting/test1.md	
@@ -0,0 +1,102 @@
+
+# Invalid URL Test Cases
+
+Here are some invalid URLs using various Markdown link and image syntaxes:
+
+- [Broken Protocol](htp://invalid-url.com)  
+  *Reason: Misspelled protocol ("htp" instead of "http")*
+
+- [No Domain](http://)  
+  *Reason: Missing domain*
+
+- [Missing Name Before TLD](http://.com)  
+  *Reason: Missing domain name before TLD*
+
+- [Underscore in Domain](http://invalid_domain)  
+  *Reason: Underscore in domain, not allowed in DNS hostnames*
+
+- [Domain Starts with Hyphen](http://-example.com)  
+  *Reason: Domain cannot start with a hyphen*
+
+- [Double Dot in Domain](http://example..com)  
+  *Reason: Double dot in domain*
+
+- [Non-numeric Port](http://example.com:abc)  
+  *Reason: Invalid port (non-numeric)*
+
+- [Unsupported Protocol](ftp://example.com)  
+  *Reason: Unsupported protocol (should be http/https)*
+
+- [Space in Domain](http://example .com)  
+  *Reason: Space in domain*
+
+- [Extra Slash in Protocol](http:///example.com)  
+  *Reason: Extra slash in protocol separator*
+
+- ![Broken Image Link](http://)  
+  *Reason: Image with missing domain*
+
+- ![Invalid Protocol Image](htp://invalid-url.com/image.png)  
+  *Reason: Image with misspelled protocol*
+
+- ![Double Dot Image](http://example..com/pic.jpg)  
+  *Reason: Image with double dot in domain*
+
+- [![Image with Bad Link](http://)](htp://invalid-url.com)  
+  *Reason: Image and link both with invalid URLs*
+
+---
+
+# Correctly Formatted but Nonexistent URLs
+
+These URLs are syntactically correct but do not point to real sites:
+
+- [Nonexistent Domain](https://this-domain-does-not-exist-123456789.com)
+
+- [Fake Subdomain](https://foo.bar.baz.nonexistent-tld)
+
+- [Unused TLD](https://example.madeuptld)
+
+- [Long Random String](https://abcdefg1234567890.example.com)
+
+- [Fake Image](https://notarealwebsite.com/image.png)
+
+- ![Nonexistent Image](https://this-image-does-not-exist.com/pic.jpg)
+
+- [![Fake Image Link](https://notarealwebsite.com/fake.png)](https://notarealwebsite.com/page)
+
+- [Unregistered Domain](https://unregistered-website-xyz.com)
+
+- [Fake Path](https://example.com/this/path/does/not/exist)
+
+- [Nonexistent Page](https://example.com/404notfound)
+
+---
+
+# Valid URLs
+
+These URLs are well-formed and point to known good sites:
+
+- [Example Domain](https://example.com)
+
+- [Wikipedia](https://en.wikipedia.org/wiki/Main_Page)
+
+- [GitHub](https://github.com)
+
+- [Google](https://www.google.com)
+
+- [Mozilla Developer Network](https://developer.mozilla.org)
+
+- [Go Documentation](https://go.dev/doc/)
+
+- ![Valid Image](https://upload.wikimedia.org/wikipedia/commons/4/47/PNG_transparency_demonstration_1.png)
+
+- [![GitHub Logo](https://github.githubassets.com/images/modules/logos_page/GitHub-Mark.png)](https://github.com)
+
+- [Svelte](https://svelte.dev)
+
+- [OpenAI](https://openai.com)
+
+
+
+
diff --git a/test files/test nesting/test2.txt b/test files/test nesting/test2.txt
new file mode 100644
index 0000000..eb470ff
--- /dev/null
+++ b/test files/test nesting/test2.txt	
@@ -0,0 +1,11 @@
+Lorem ipsum dolor sit amet, consectetur adipiscing elit. Sed euismod, urna eu tincidunt consectetur, nisi nisl aliquam enim, eget facilisis quam felis id mauris. 
+Check out this website: https://example.com for more information. 
+Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia curae; Mauris non tempor quam.
+
+Phasellus euismod, justo at dictum placerat, sapien erat ultricies eros, ac porta sem ex ac nisi. 
+For documentation, visit https://docs.something.org or refer to https://github.com/example/repo for the source code.
+Nullam ac urna eu felis dapibus condimentum sit amet a augue.
+
+Curabitur non nulla sit amet nisl tempus convallis quis ac lectus. 
+You might also find https://news.ycombinator.com interesting for tech news.
+Vivamus magna justo, lacinia eget consectetur sed, convallis at tellus.
diff --git a/test files/test10.log b/test files/test10.log
new file mode 100644
index 0000000..415514f
--- /dev/null
+++ b/test files/test10.log	
@@ -0,0 +1,11 @@
+2025-09-10 10:00:00 INFO Fetching https://example.com
+2025-09-10 10:00:01 INFO Fetching https://github.com/example/repo
+2025-09-10 10:00:02 WARN Retrying htp://bad-protocol.com
+2025-09-10 10:00:03 ERROR Failed to fetch http:///example.com
+2025-09-10 10:00:04 ERROR DNS error for https://this-domain-does-not-exist-123456789.com
+2025-09-10 10:00:05 INFO Fetching http://example.com:8080/api/status
+2025-09-10 10:00:06 ERROR Invalid host http://example..com
+2025-09-10 10:00:07 ERROR Missing domain https://
+2025-09-10 10:00:08 INFO Fetching https://en.wikipedia.org/wiki/Main_Page
+
+
diff --git a/test files/test11.go b/test files/test11.go
new file mode 100644
index 0000000..b1a2e05
--- /dev/null
+++ b/test files/test11.go	
@@ -0,0 +1,10 @@
+package testfiles
+
+// Sample Go file with URLs
+var url1 = "https://example.com"
+var url2 = "https://en.wikipedia.org/wiki/Main_Page"
+var urlBad = "http://example..com"
+var urlMissing = "https://"
+var urlNonexistent = "https://this-domain-does-not-exist-123456789.com"
+var urlPlaceholder1 = "https://[tenant].api.identitynow.com"
+var urlPlaceholder2 = "https://{tenant}.api.identitynow.com"
diff --git a/test files/test12.php b/test files/test12.php
new file mode 100644
index 0000000..5d4db75
--- /dev/null
+++ b/test files/test12.php	
@@ -0,0 +1,11 @@
+<?php
+// Sample PHP file with URLs
+$url1 = "https://developer.mozilla.org";
+$url2 = "https://github.com/example/repo";
+$urlBad = "http://example..com";
+$urlMissing = "https://";
+$urlNonexistent = "https://notarealwebsite.com/image.png";
+$urlPlaceholder = "https://{tenant}.api.identitynow.com";
+?>
+
+
diff --git a/test files/test13.ps1 b/test files/test13.ps1
new file mode 100644
index 0000000..6464693
--- /dev/null
+++ b/test files/test13.ps1	
@@ -0,0 +1,9 @@
+# Sample PowerShell file with URLs
+$url1 = "https://example.com"
+$url2 = "https://news.ycombinator.com"
+$urlBad = "http://example..com"
+$urlMissing = "https://"
+$urlNonexistent = "https://example.madeuptld"
+$urlPlaceholder = "https://[tenant].api.identitynow.com"
+
+
diff --git a/test files/test14.py b/test files/test14.py
new file mode 100644
index 0000000..6b434b3
--- /dev/null
+++ b/test files/test14.py	
@@ -0,0 +1,9 @@
+# Sample Python file with URLs
+url1 = "https://example.com"
+url2 = "https://developer.mozilla.org"
+url_bad = "http://example..com"
+url_missing = "https://"
+url_nonexistent = "https://this-image-domain-should-not-exist-xyz.example"
+url_placeholder = "https://{tenant}.api.identitynow.com/v3/transforms"
+
+
diff --git a/test files/test15.java b/test files/test15.java
new file mode 100644
index 0000000..f74c137
--- /dev/null
+++ b/test files/test15.java	
@@ -0,0 +1,11 @@
+public class Test15 {
+    // Sample Java file with URLs
+    String url1 = "https://example.com";
+    String url2 = "https://svelte.dev";
+    String urlBad = "http://example..com";
+    String urlMissing = "https://";
+    String urlNonexistent = "https://unregistered-website-xyz.com";
+    String urlPlaceholder = "https://[tenant].[domain].com";
+}
+
+
diff --git a/test files/test16.ts b/test files/test16.ts
new file mode 100644
index 0000000..16d2324
--- /dev/null
+++ b/test files/test16.ts	
@@ -0,0 +1,9 @@
+// Sample TypeScript file with URLs
+const url1: string = "https://example.com";
+const url2: string = "https://go.dev/doc/";
+const urlBad: string = "http://example..com";
+const urlMissing: string = "https://";
+const urlNonexistent: string = "https://this-domain-does-not-exist-987654321.com";
+const urlPlaceholder: string = "https://{tenant}.api.ideidentitynow.com/v3/transforms";
+
+
diff --git a/test files/test17.rb b/test files/test17.rb
new file mode 100644
index 0000000..a454c44
--- /dev/null
+++ b/test files/test17.rb	
@@ -0,0 +1,9 @@
+# Sample Ruby file with URLs
+url1 = "https://example.com"
+url2 = "https://github.com"
+url_bad = "http://example..com"
+url_missing = "https://"
+url_nonexistent = "https://totally-made-up-host-tld-abcdef123.com"
+url_placeholder = "https://[tenant].api.identitynow.com"
+
+
diff --git a/test files/test3.js b/test files/test3.js
new file mode 100644
index 0000000..c2b64c8
--- /dev/null
+++ b/test files/test3.js	
@@ -0,0 +1,5 @@
+const link1 = "https://example.com";
+const link2 = "https://docs.something.org";
+const link3 = "https://github.com/example/repo";
+const link4 = "https://news.ycombinator.com";
+const link5 = "http://example.com:8080";
diff --git a/test files/test4.xml b/test files/test4.xml
new file mode 100644
index 0000000..3f4b277
--- /dev/null
+++ b/test files/test4.xml	
@@ -0,0 +1,7 @@
+<links>
+  <link>https://example.com</link>
+  <link>https://docs.something.org</link>
+  <link>https://github.com/example/repo</link>
+  <link>https://news.ycombinator.com</link>
+  <link>http://example.com:8080</link>
+</links>
diff --git a/test files/test5.html b/test files/test5.html
new file mode 100644
index 0000000..c081d9f
--- /dev/null
+++ b/test files/test5.html	
@@ -0,0 +1,25 @@
+<!DOCTYPE html>
+<html>
+<head>
+  <meta charset="utf-8">
+  <title>URL Test HTML</title>
+</head>
+<body>
+  <h1>URL Test Links</h1>
+  <a href="https://example.com">Example</a>
+  <a href="http://example.com:8080/path?query=1">With Port</a>
+  <a href="htp://bad-protocol.com">Bad Protocol</a>
+  <a href="https://">Missing Domain</a>
+  <a href="http:///example.com">Extra Slash</a>
+  <a href="http://example..com">Double Dot</a>
+  <a href="https://this-domain-does-not-exist-123456789.com">Nonexistent Domain</a>
+  <a href="https://en.wikipedia.org/wiki/Main_Page">Wikipedia</a>
+
+  <h2>Images</h2>
+  <img src="https://upload.wikimedia.org/wikipedia/commons/4/47/PNG_transparency_demonstration_1.png" alt="Valid Image">
+  <img src="http://example..com/pic.jpg" alt="Double Dot Image">
+  <img src="htp://invalid-url.com/image.png" alt="Bad Protocol Image">
+</body>
+</html>
+
+
diff --git a/test files/test6.json b/test files/test6.json
new file mode 100644
index 0000000..d768c41
--- /dev/null
+++ b/test files/test6.json	
@@ -0,0 +1,21 @@
+{
+  "valid": [
+    "https://example.com",
+    "https://github.com",
+    "http://example.com:8080/path",
+    "https://en.wikipedia.org/wiki/Main_Page"
+  ],
+  "invalid": [
+    "htp://invalid-url.com",
+    "http:///example.com",
+    "http://example..com",
+    "https://"
+  ],
+  "nonexistent": [
+    "https://this-domain-does-not-exist-123456789.com",
+    "https://notarealwebsite.com/image.png",
+    "https://example.madeuptld"
+  ]
+}
+
+
diff --git a/test files/test7.yaml b/test files/test7.yaml
new file mode 100644
index 0000000..5f7bcb1
--- /dev/null
+++ b/test files/test7.yaml	
@@ -0,0 +1,15 @@
+valid:
+  - https://example.com
+  - https://docs.something.org
+  - http://example.com:8080/path
+invalid:
+  - htp://bad-protocol.com
+  - http:///too-many-slashes.com
+  - http://example..com
+  - https://
+nonexistent:
+  - https://notarealwebsite.com/page
+  - https://unregistered-website-xyz.com
+  - https://example.madeuptld
+
+
diff --git a/test files/test8.csv b/test files/test8.csv
new file mode 100644
index 0000000..42b07b9
--- /dev/null
+++ b/test files/test8.csv	
@@ -0,0 +1,13 @@
+id,name,url
+1,Example,https://example.com
+2,Docs,https://docs.something.org
+3,Repo,https://github.com/example/repo
+4,HN,https://news.ycombinator.com
+5,WithPort,http://example.com:8080
+6,BadProtocol,htp://invalid-url.com
+7,ExtraSlash,http:///example.com
+8,DoubleDot,http://example..com
+9,MissingDomain,https://
+10,Nonexistent,https://this-domain-does-not-exist-123456789.com
+
+
diff --git a/test files/test9.ini b/test files/test9.ini
new file mode 100644
index 0000000..9784d05
--- /dev/null
+++ b/test files/test9.ini	
@@ -0,0 +1,12 @@
+[links]
+good1 = https://example.com
+good2 = https://en.wikipedia.org/wiki/Main_Page
+good3 = http://example.com:8080/path
+bad1 = htp://bad-protocol.com
+bad2 = http:///example.com
+bad3 = http://example..com
+missing = https://
+nonexistent1 = https://notarealwebsite.com/image.png
+nonexistent2 = https://example.madeuptld
+
+