diff --git a/.gitea/workflows/build-binaries.yml b/.gitea/workflows/build-binaries.yml
new file mode 100644
index 0000000..f4f5770
--- /dev/null
+++ b/.gitea/workflows/build-binaries.yml
@@ -0,0 +1,66 @@
+# Cross-platform Crucible binaries (D7 trigger standard):
+#   PR / push main -> cross-build ALL targets to prove they compile (no publish)
+#   tag v*         -> build all targets + SHA256SUMS, upload to the Gitea release
+# Crucible is pure Go (CGO_ENABLED=0), so cross-compiling is a fast loop.
+name: build-binaries
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+    tags: ['v*']
+
+jobs:
+  build-binaries:
+    runs-on: nix-docker
+    steps:
+      - uses: actions/checkout@v4
+        with: { fetch-depth: 0 }
+
+      - name: Cross-build all targets
+        run: |
+          nix develop --command bash -c '
+            set -euo pipefail
+            sha="$(git rev-parse --short=12 HEAD)"
+            ldflags="-s -w -X git.westgate.pw/ShadowsOverWestgate/sow-tools/internal/buildinfo.Version=${sha}"
+            rm -rf dist && mkdir -p dist
+            export CGO_ENABLED=0
+            for target in linux/amd64 linux/arm64 darwin/amd64 darwin/arm64 windows/amd64 windows/arm64; do
+              os="${target%/*}"; arch="${target#*/}"
+              ext=""; [ "$os" = windows ] && ext=".exe"
+              echo "building crucible-${os}-${arch}${ext}"
+              GOOS="$os" GOARCH="$arch" go build -trimpath -ldflags "$ldflags" \
+                -o "dist/crucible-${os}-${arch}${ext}" ./cmd/crucible
+            done
+            # Ship the canonical wrappers as release assets too: consumer
+            # drift-check fetches them from the latest release to compare.
+            cp wrappers/crucible.sh wrappers/crucible.ps1 dist/
+            ( cd dist && sha256sum crucible-* > SHA256SUMS )
+            cat dist/SHA256SUMS
+          '
+
+      - name: Upload to Gitea release
+        if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags/v')
+        env:
+          TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          TAG: ${{ github.ref_name }}
+          REPO: ${{ github.repository }}
+          SERVER: ${{ github.server_url }}
+        run: |
+          nix develop --command bash -c '
+            set -euo pipefail
+            api="${SERVER}/api/v1/repos/${REPO}"
+            auth="Authorization: token ${TOKEN}"
+            # Create the release (ignore "already exists"), then read its id.
+            curl -fsS -X POST -H "$auth" -H "Content-Type: application/json" \
+              "${api}/releases" \
+              -d "{\"tag_name\":\"${TAG}\",\"name\":\"${TAG}\"}" || true
+            id="$(curl -fsS -H "$auth" "${api}/releases/tags/${TAG}" \
+              | grep -o "\"id\":[0-9]*" | head -1 | cut -d: -f2)"
+            for f in dist/*; do
+              echo "uploading $(basename "$f")"
+              curl -fsS -X POST -H "$auth" \
+                -F "attachment=@${f}" \
+                "${api}/releases/${id}/assets?name=$(basename "$f")"
+            done
+          '
diff --git a/.gitea/workflows/build-image.yml b/.gitea/workflows/build-image.yml
index eeba638..6bfaeb7 100644
--- a/.gitea/workflows/build-image.yml
+++ b/.gitea/workflows/build-image.yml
@@ -9,7 +9,7 @@ name: build-image
 
 on:
   push:
-    tags: ["v*"]
+    tags: ['v*']
 
 env:
   REGISTRY: registry.westgate.pw
@@ -29,6 +29,7 @@ jobs:
       - name: Build OCI image (daemonless)
         run: nix build .#image
 
+      # This workflow only runs on v* tags, so every run is a release publish.
       - name: Publish image
         env:
           REGISTRY_USER: ${{ secrets.REGISTRY_USER }}
diff --git a/.gitea/workflows/release.yml b/.gitea/workflows/release.yml
deleted file mode 100644
index e7caf19..0000000
--- a/.gitea/workflows/release.yml
+++ /dev/null
@@ -1,38 +0,0 @@
-# Tag a Crucible release: re-tag the already-built immutable image and attach
-# per-platform binary bundles. Tag-gated; never PR-triggered (deploy/release is
-# not a PR concern, D7). The :<sha> image from build-image is the source of truth.
-name: release
-
-on:
-  push:
-    tags:
-      - "v*"
-
-env:
-  REGISTRY: registry.westgate.pw
-  IMAGE: deployment/crucible
-
-jobs:
-  release:
-    runs-on: nix-docker
-    steps:
-      - uses: actions/checkout@v4
-        with: { fetch-depth: 0 }
-
-      - name: Build release binaries
-        run: |
-          nix develop --command bash -c '
-            set -euo pipefail
-            GOOS=linux   GOARCH=amd64 bash scripts/build-binaries.sh
-            mkdir -p dist
-            tar -C bin -czf "dist/crucible-linux-amd64-${GITHUB_REF_NAME}.tar.gz" .
-          '
-
-      - name: Upload release artifacts
-        uses: actions/upload-artifact@v4
-        with:
-          name: crucible-${{ github.ref_name }}
-          path: dist/*
-
-      # TODO(phase-6): re-tag registry.westgate.pw/deployment/crucible:<sha> as :<tag>
-      # and pin it from sow-platform releases/*.yml once the registry is live.
diff --git a/internal/dispatch/dispatch.go b/internal/dispatch/dispatch.go
index ece2879..2f53572 100644
--- a/internal/dispatch/dispatch.go
+++ b/internal/dispatch/dispatch.go
@@ -17,6 +17,7 @@ import (
 
 	"git.westgate.pw/ShadowsOverWestgate/sow-tools/internal/app"
 	"git.westgate.pw/ShadowsOverWestgate/sow-tools/internal/buildinfo"
+	"git.westgate.pw/ShadowsOverWestgate/sow-tools/internal/menu"
 )
 
 // Exit codes follow the sysexits(3) convention so CI can distinguish
@@ -103,8 +104,52 @@ func find(name string) (Builder, bool) {
 	return Builder{}, false
 }
 
-// Main is the `crucible` dispatcher entrypoint.
-func Main(args []string) int { return run(args, os.Stdout, os.Stderr) }
+// Main is the `crucible` dispatcher entrypoint. With no arguments on an
+// interactive terminal it launches the menu; otherwise (pipes, CI) it prints
+// usage, preserving scriptable behavior.
+func Main(args []string) int {
+	if len(args) == 0 && interactive(os.Stdout) {
+		return runMenu(os.Stdout, os.Stderr, os.Stdin)
+	}
+	return run(args, os.Stdout, os.Stderr)
+}
+
+func interactive(f *os.File) bool {
+	fi, err := f.Stat()
+	if err != nil {
+		return false
+	}
+	return fi.Mode()&os.ModeCharDevice != 0
+}
+
+func menuItems() []menu.Item {
+	var items []menu.Item
+	for _, b := range Registry {
+		if !b.Wired {
+			continue
+		}
+		for _, sub := range b.subcommands() {
+			items = append(items, menu.Item{
+				Label: b.Name + " " + sub,
+				Desc:  b.Summary,
+				Args:  []string{b.Name, sub},
+			})
+		}
+	}
+	return items
+}
+
+func runMenu(out, errw io.Writer, in io.Reader) int {
+	chosen, err := menu.Select(out, in, menuItems())
+	if err != nil {
+		fmt.Fprintln(errw, "crucible:", err)
+		return exitUsage
+	}
+	if chosen == nil {
+		return exitOK
+	}
+	return run(chosen, out, errw)
+}
 
 // RunBuilder is the standalone `crucible-<name>` entrypoint.
 func RunBuilder(name string, args []string) int {
diff --git a/internal/dispatch/dispatch_test.go b/internal/dispatch/dispatch_test.go
index f5ce543..7315f21 100644
--- a/internal/dispatch/dispatch_test.go
+++ b/internal/dispatch/dispatch_test.go
@@ -135,3 +135,22 @@ func TestLegacyCommandsHaveExactlyOneHome(t *testing.T) {
 		}
 	}
 }
+
+func TestMenuItemsSkipsUnwiredIncludesWired(t *testing.T) {
+	items := menuItems()
+	if len(items) == 0 {
+		t.Fatal("expected menu items")
+	}
+	sawModuleBuild := false
+	for _, it := range items {
+		if it.Args[0] == "depot" {
+			t.Errorf("unwired builder %q must not appear in the menu", it.Args[0])
+		}
+		if len(it.Args) == 2 && it.Args[0] == "module" && it.Args[1] == "build" {
+			sawModuleBuild = true
+		}
+	}
+	if !sawModuleBuild {
+		t.Error("expected 'module build' in the menu")
+	}
+}
diff --git a/internal/menu/menu.go b/internal/menu/menu.go
new file mode 100644
index 0000000..9503d18
--- /dev/null
+++ b/internal/menu/menu.go
@@ -0,0 +1,60 @@
+// Package menu renders Crucible's interactive launcher: a numbered list of
+// commands for users who don't want to memorize subcommands. It holds no
+// builder logic — it returns the chosen dispatcher argument slice for the
+// caller to run. This is the seed of a future GUI front-end over the same core.
+package menu
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"strconv"
+	"strings"
+)
+
+// Item is one selectable command.
+type Item struct {
+	Label string   // e.g. "module build"
+	Desc  string   // e.g. "build/extract/validate/compare the .mod"
+	Args  []string // dispatcher args, e.g. {"module", "build"}
+}
+
+// ANSI styling; terminals that don't support it simply ignore the codes.
+const (
+	cReset = "\033[0m"
+	cBold  = "\033[1m"
+	cCyan  = "\033[36m"
+	cDim   = "\033[2m"
+)
+
+// Select prints the numbered menu to out, reads a selection plus optional extra
+// arguments from in, and returns the full dispatcher argument slice. It returns
+// (nil, nil) when the user quits or enters an empty choice.
+func Select(out io.Writer, in io.Reader, items []Item) ([]string, error) {
+	if len(items) == 0 {
+		return nil, fmt.Errorf("no commands available")
+	}
+	fmt.Fprintf(out, "%s%sCrucible%s — pick a command:\n\n", cBold, cCyan, cReset)
+	for i, it := range items {
+		fmt.Fprintf(out, "  %s%2d%s  %s%-24s%s %s%s%s\n",
+			cCyan, i+1, cReset, cBold, it.Label, cReset, cDim, it.Desc, cReset)
+	}
+	fmt.Fprintf(out, "   %sq%s  quit\n\nselection: ", cCyan, cReset)
+
+	r := bufio.NewReader(in)
+	line, _ := r.ReadString('\n')
+	switch choice := strings.TrimSpace(line); choice {
+	case "", "q", "Q":
+		return nil, nil
+	default:
+		n, err := strconv.Atoi(choice)
+		if err != nil || n < 1 || n > len(items) {
+			return nil, fmt.Errorf("invalid selection %q", choice)
+		}
+		it := items[n-1]
+		fmt.Fprintf(out, "extra args for %q (optional): ", it.Label)
+		argLine, _ := r.ReadString('\n')
+		extra := strings.Fields(strings.TrimSpace(argLine))
+		return append(append([]string{}, it.Args...), extra...), nil
+	}
+}
diff --git a/internal/menu/menu_test.go b/internal/menu/menu_test.go
new file mode 100644
index 0000000..3fe284d
--- /dev/null
+++ b/internal/menu/menu_test.go
@@ -0,0 +1,47 @@
+package menu
+
+import (
+	"io"
+	"reflect"
+	"strings"
+	"testing"
+)
+
+var sample = []Item{
+	{Label: "module build", Desc: "build the .mod", Args: []string{"module", "build"}},
+	{Label: "topdata validate-topdata", Desc: "validate topdata", Args: []string{"topdata", "validate-topdata"}},
+}
+
+func TestSelectReturnsChosenArgs(t *testing.T) {
+	got, err := Select(io.Discard, strings.NewReader("1\n\n"), sample)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if want := []string{"module", "build"}; !reflect.DeepEqual(got, want) {
+		t.Fatalf("got %v, want %v", got, want)
+	}
+}
+
+func TestSelectAppendsExtraArgs(t *testing.T) {
+	got, err := Select(io.Discard, strings.NewReader("2\n--dry-run foo\n"), sample)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	want := []string{"topdata", "validate-topdata", "--dry-run", "foo"}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("got %v, want %v", got, want)
+	}
+}
+
+func TestSelectQuitReturnsNil(t *testing.T) {
+	got, err := Select(io.Discard, strings.NewReader("q\n"), sample)
+	if err != nil || got != nil {
+		t.Fatalf("quit should return (nil,nil); got (%v,%v)", got, err)
+	}
+}
+
+func TestSelectInvalidErrors(t *testing.T) {
+	if _, err := Select(io.Discard, strings.NewReader("99\n"), sample); err == nil {
+		t.Fatal("out-of-range selection should error")
+	}
+}
diff --git a/internal/music/music.go b/internal/music/music.go
index 64584e5..d68ec3d 100644
--- a/internal/music/music.go
+++ b/internal/music/music.go
@@ -1,6 +1,7 @@
 package music
 
 import (
+	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -104,7 +105,7 @@ func ResolveFFmpegWithConfig(configuredPath string) (string, error) {
 	}
 	path, err := exec.LookPath("ffmpeg")
 	if err != nil {
-		return "", err
+		return "", ffmpegMissingErr("ffmpeg")
 	}
 	return path, nil
 }
@@ -122,11 +123,23 @@ func ResolveFFprobeWithConfig(configuredPath string) (string, error) {
 	}
 	path, err := exec.LookPath("ffprobe")
 	if err != nil {
-		return "", err
+		return "", ffmpegMissingErr("ffprobe")
 	}
 	return path, nil
 }
 
+// ffmpegMissingErr renders an actionable, cross-platform "tool not found"
+// message. Only the music builder needs ffmpeg/ffprobe; every other builder
+// runs with zero external dependencies.
+func ffmpegMissingErr(tool string) error {
+	return fmt.Errorf(`%[1]s not found on PATH.
+  Windows: winget install Gyan.FFmpeg
+  macOS:   brew install ffmpeg
+  Linux:   apt install ffmpeg   (or your distro's package manager)
+Only the music builder needs %[1]s; set SOW_%[2]s to a full path to override.`,
+		tool, strings.ToUpper(tool))
+}
+
 func IsMusicAssetPath(rel string) bool {
 	rel = filepath.ToSlash(strings.TrimSpace(rel))
 	return rel == "envi/music" || strings.HasPrefix(rel, "envi/music/")
diff --git a/internal/music/music_test.go b/internal/music/music_test.go
index ba33de3..bb11d12 100644
--- a/internal/music/music_test.go
+++ b/internal/music/music_test.go
@@ -402,3 +402,16 @@ func TestResolveFFprobeEnv(t *testing.T) {
 		t.Fatalf("expected '/custom/ffprobe', got %q", path)
 	}
 }
+
+func TestFFmpegMissingErrHasInstallHints(t *testing.T) {
+	msg := ffmpegMissingErr("ffmpeg").Error()
+	for _, want := range []string{"ffmpeg", "winget", "brew", "apt", "SOW_FFMPEG"} {
+		if !strings.Contains(msg, want) {
+			t.Errorf("ffmpeg error missing %q; got:\n%s", want, msg)
+		}
+	}
+	probe := ffmpegMissingErr("ffprobe").Error()
+	if !strings.Contains(probe, "SOW_FFPROBE") {
+		t.Errorf("ffprobe error should mention SOW_FFPROBE; got:\n%s", probe)
+	}
+}
diff --git a/wrappers/crucible.ps1 b/wrappers/crucible.ps1
new file mode 100644
index 0000000..0762977
--- /dev/null
+++ b/wrappers/crucible.ps1
@@ -0,0 +1,89 @@
+#!/usr/bin/env pwsh
+# crucible - bootstrap wrapper (PowerShell). Prefers a crucible already on PATH;
+# otherwise downloads the latest released binary from Gitea into a per-version
+# cache and execs it.
+#
+# CANONICAL SOURCE: sow-tools/wrappers/crucible.ps1. Do not hand-edit copies in
+# consumer repos - kept in sync by sow-tools CI (see drift-check).
+#
+# Env: CRUCIBLE_HOME, CRUCIBLE_TOKEN, CRUCIBLE_GITEA, CRUCIBLE_REPO.
+$ErrorActionPreference = 'Stop'
+
+# 0. Prefer an existing crucible.
+$existing = Get-Command crucible -ErrorAction SilentlyContinue
+if ($existing) { & $existing.Source @args; exit $LASTEXITCODE }
+
+$gitea = if ($env:CRUCIBLE_GITEA) { $env:CRUCIBLE_GITEA } else { 'https://git.westgate.pw' }
+$repo  = if ($env:CRUCIBLE_REPO)  { $env:CRUCIBLE_REPO }  else { 'ShadowsOverWestgate/sow-tools' }
+
+# 1. OS/arch -> asset name (.exe on Windows).
+$os = if ($IsWindows) { 'windows' } elseif ($IsMacOS) { 'darwin' } else { 'linux' }
+$arch = switch ($env:PROCESSOR_ARCHITECTURE) {
+  'AMD64' { 'amd64' } 'ARM64' { 'arm64' } default { 'amd64' }
+}
+$ext = if ($os -eq 'windows') { '.exe' } else { '' }
+$asset = "crucible-$os-$arch$ext"
+
+# 2. Auth header (anon first, token fallback).
+$token = $env:CRUCIBLE_TOKEN
+$tokenFile = Join-Path $HOME '.config/crucible/token'
+if (-not $token -and (Test-Path $tokenFile)) { $token = (Get-Content $tokenFile -Raw).Trim() }
+function Invoke-Fetch($url, $outFile) {
+  try { Invoke-WebRequest -Uri $url -OutFile $outFile -UseBasicParsing; return $true } catch {}
+  if ($token) {
+    Invoke-WebRequest -Uri $url -OutFile $outFile -UseBasicParsing -Headers @{ Authorization = "token $token" }
+    return $true
+  }
+  return $false
+}
+
+# 3. Resolve latest tag.
+$tag = $null
+try {
+  $hdr = if ($token) { @{ Authorization = "token $token" } } else { @{} }
+  $rel = Invoke-RestMethod -Uri "$gitea/api/v1/repos/$repo/releases/latest" -Headers $hdr
+  $tag = $rel.tag_name
+} catch {}
+
+# 4. Cache dir.
+$cacheRoot = if ($env:CRUCIBLE_HOME) { $env:CRUCIBLE_HOME }
+  elseif ($env:LOCALAPPDATA) { Join-Path $env:LOCALAPPDATA 'crucible' }
+  else { Join-Path $HOME '.cache/crucible' }
+
+# 5. Offline fallback.
+if (-not $tag) {
+  if (Test-Path $cacheRoot) {
+    $cached = Get-ChildItem $cacheRoot -Directory | Sort-Object Name | Select-Object -Last 1
+    $cachedBin = if ($cached) { Join-Path $cached.FullName "crucible$ext" } else { $null }
+    if ($cachedBin -and (Test-Path $cachedBin)) {
+      Write-Error "crucible: offline - using cached $($cached.Name)" -ErrorAction Continue
+      & $cachedBin @args; exit $LASTEXITCODE
+    }
+  }
+  Write-Error "crucible: cannot reach $gitea and no cached binary found (set CRUCIBLE_TOKEN if private)."
+  exit 1
+}
+
+$destDir = Join-Path $cacheRoot $tag
+$bin = Join-Path $destDir "crucible$ext"
+
+# 6. Download + verify on cache miss.
+if (-not (Test-Path $bin)) {
+  New-Item -ItemType Directory -Force -Path $destDir | Out-Null
+  $base = "$gitea/$repo/releases/download/$tag"
+  $tmp = New-Item -ItemType Directory -Path (Join-Path ([System.IO.Path]::GetTempPath()) ([guid]::NewGuid()))
+  $tmpBin = Join-Path $tmp "crucible$ext"
+  Write-Host "crucible: fetching $asset $tag..."
+  if (-not (Invoke-Fetch "$base/$asset" $tmpBin)) { Write-Error "crucible: download failed for $asset"; exit 1 }
+  $sums = Join-Path $tmp 'SHA256SUMS'
+  if (Invoke-Fetch "$base/SHA256SUMS" $sums) {
+    $want = (Select-String -Path $sums -Pattern ([regex]::Escape($asset) + '$') | Select-Object -First 1).Line -split '\s+' | Select-Object -First 1
+    $got = (Get-FileHash $tmpBin -Algorithm SHA256).Hash.ToLower()
+    if ($want -and ($want.ToLower() -ne $got)) { Write-Error "crucible: checksum mismatch for $asset"; exit 1 }
+  }
+  Move-Item -Force $tmpBin $bin
+  Remove-Item -Recurse -Force $tmp
+}
+
+& $bin @args
+exit $LASTEXITCODE
diff --git a/wrappers/crucible.sh b/wrappers/crucible.sh
new file mode 100755
index 0000000..cae4637
--- /dev/null
+++ b/wrappers/crucible.sh
@@ -0,0 +1,107 @@
+#!/usr/bin/env bash
+# crucible — bootstrap wrapper (POSIX/bash). Prefers a crucible already on PATH
+# (Nix devshell / installed); otherwise downloads the latest released binary
+# from Gitea into a per-version cache and execs it.
+#
+# CANONICAL SOURCE: sow-tools/wrappers/crucible.sh. Do not hand-edit copies in
+# consumer repos — they are kept in sync by sow-tools CI (see drift-check).
+#
+# Requires: bash, curl, and sha256sum (Linux) or shasum (macOS).
+# Env: CRUCIBLE_HOME (cache dir), CRUCIBLE_TOKEN (private releases),
+#      CRUCIBLE_GITEA (default https://git.westgate.pw),
+#      CRUCIBLE_REPO (default ShadowsOverWestgate/sow-tools).
+set -euo pipefail
+
+# 0. Prefer an existing crucible (Nix users, or already installed).
+if command -v crucible >/dev/null 2>&1; then
+  exec crucible "$@"
+fi
+
+gitea="${CRUCIBLE_GITEA:-https://git.westgate.pw}"
+repo="${CRUCIBLE_REPO:-ShadowsOverWestgate/sow-tools}"
+
+# 1. --repo-local materializes into <repo>/.crucible instead of the user cache.
+repo_local=0
+if [ "${1:-}" = "--repo-local" ]; then repo_local=1; shift; fi
+
+# 2. OS/arch -> asset name.
+os="$(uname -s)"; arch="$(uname -m)"
+case "$os" in
+  Linux)  os=linux ;;
+  Darwin) os=darwin ;;
+  *) echo "crucible: unsupported OS '$os' — install ffmpeg-free crucible manually" >&2; exit 1 ;;
+esac
+case "$arch" in
+  x86_64|amd64)  arch=amd64 ;;
+  aarch64|arm64) arch=arm64 ;;
+  *) echo "crucible: unsupported arch '$arch'" >&2; exit 1 ;;
+esac
+asset="crucible-${os}-${arch}"
+
+# 3. Auth: anonymous first, token fallback.
+token="${CRUCIBLE_TOKEN:-}"
+if [ -z "$token" ] && [ -f "$HOME/.config/crucible/token" ]; then
+  token="$(cat "$HOME/.config/crucible/token")"
+fi
+fetch() { # fetch URL DEST ; tries anon then token
+  if curl -fsSL "$1" -o "$2" 2>/dev/null; then return 0; fi
+  if [ -n "$token" ]; then curl -fsSL -H "Authorization: token $token" "$1" -o "$2"; return $?; fi
+  return 1
+}
+fetch_stdout() { # prints body; anon then token
+  if curl -fsSL "$1" 2>/dev/null; then return 0; fi
+  if [ -n "$token" ]; then curl -fsSL -H "Authorization: token $token" "$1"; return $?; fi
+  return 1
+}
+
+# 4. Resolve the latest release tag (no jq dependency).
+api="${gitea}/api/v1/repos/${repo}/releases/latest"
+tag="$(fetch_stdout "$api" 2>/dev/null | grep -o '"tag_name":"[^"]*"' | head -1 | cut -d'"' -f4 || true)"
+
+# 5. Cache dir.
+if [ "$repo_local" = 1 ]; then
+  cache_root="$(cd "$(dirname "$0")" && pwd)/.crucible"
+else
+  cache_root="${CRUCIBLE_HOME:-${XDG_CACHE_HOME:-$HOME/.cache}/crucible}"
+fi
+
+# 6. Offline fallback: if tag lookup failed, use the newest cached version.
+if [ -z "$tag" ]; then
+  if [ -d "$cache_root" ]; then
+    cached="$(ls -1 "$cache_root" 2>/dev/null | sort -V | tail -1 || true)"
+    if [ -n "$cached" ] && [ -x "$cache_root/$cached/crucible" ]; then
+      echo "crucible: offline — using cached $cached" >&2
+      exec "$cache_root/$cached/crucible" "$@"
+    fi
+  fi
+  echo "crucible: cannot reach $gitea and no cached binary found." >&2
+  echo "  set CRUCIBLE_TOKEN if releases are private, or check the network." >&2
+  exit 1
+fi
+
+dest_dir="$cache_root/$tag"
+bin="$dest_dir/crucible"
+
+# 7. Download + verify on cache miss.
+if [ ! -x "$bin" ]; then
+  mkdir -p "$dest_dir"
+  base="${gitea}/${repo}/releases/download/${tag}"
+  tmp="$(mktemp -d)"; trap 'rm -rf "$tmp"' EXIT
+  echo "crucible: fetching ${asset} ${tag}..." >&2
+  fetch "${base}/${asset}" "$tmp/crucible" || { echo "crucible: download failed for ${asset}" >&2; exit 1; }
+  if fetch "${base}/SHA256SUMS" "$tmp/SHA256SUMS"; then
+    want="$(grep " ${asset}\$" "$tmp/SHA256SUMS" | awk '{print $1}')"
+    if command -v sha256sum >/dev/null 2>&1; then
+      got="$(sha256sum "$tmp/crucible" | awk '{print $1}')"
+    else
+      got="$(shasum -a 256 "$tmp/crucible" | awk '{print $1}')"
+    fi
+    if [ -n "$want" ] && [ "$want" != "$got" ]; then
+      echo "crucible: checksum mismatch for ${asset} (want $want got $got)" >&2; exit 1
+    fi
+  fi
+  chmod +x "$tmp/crucible"
+  mv "$tmp/crucible" "$bin"
+fi
+
+exec "$bin" "$@"