diff --git a/tools/audit/audit-dep-currency.ts b/tools/audit/audit-dep-currency.ts
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+++ b/tools/audit/audit-dep-currency.ts
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+#!/usr/bin/env bun
+// tools/audit/audit-dep-currency.ts
+//
+// B-0805 sub-target 1 — initial implementation. Scans dep pins across
+// the repo + reports staleness against upstream-current versions.
+//
+// Scope (this initial implementation; sub-target 2+ will extend):
+//   1. full-ai-cluster/flake.nix → nixpkgs.url + nix-darwin.url
+//   2. ArgoCD Application files under full-ai-cluster/k8s/applications/
+//      → spec.source.targetRevision + spec.source.helm.chart
+//   3. Container image tags referenced in NixOS modules + K8s manifests
+//      (line-level grep for `image: <repo>:<tag>` patterns)
+//   4. .mise.toml runtime versions (if file exists)
+//
+// What it DOES NOT do yet (file as sibling B-NNNN rows when ready):
+//   - WebSearch / upstream-API calls for "current latest" — initial
+//     output is INVENTORY ONLY (lists all pin-sites + values; operator
+//     compares against upstream); follow-on row adds the
+//     upstream-comparison step
+//   - Weekly cadence GitHub Actions wiring — separate row
+//   - PR-opening on drift detection — separate row
+//
+// This row's deliverable is the INVENTORY substrate: a single TS tool
+// that enumerates everywhere in the repo where a version pin lives.
+// That output IS the load-bearing input every other sub-target consumes.
+//
+// Usage:
+//   bun tools/audit/audit-dep-currency.ts          # human-readable table
+//   bun tools/audit/audit-dep-currency.ts --json   # machine-readable JSON
+//
+// Exit codes:
+//   0 — inventory completed (always; no version comparison done yet)
+//   1 — invocation error
+
+import { existsSync, readFileSync, readdirSync, statSync } from "node:fs";
+import { join, relative } from "node:path";
+import { spawnSync } from "node:child_process";
+
+interface DepPin {
+  category: "nix-input" | "argocd-target" | "argocd-helm-chart" | "image-tag" | "mise-runtime";
+  file: string;
+  line: number;
+  name: string;
+  currentPin: string;
+}
+
+interface Args {
+  jsonOutput: boolean;
+  repoRoot: string;
+}
+
+interface ArgError {
+  error: string;
+}
+
+function resolveRepoRoot(): string | null {
+  // spawnSync with explicit args[] array (NOT a shell-evaluated string)
+  // is the execFile-equivalent safe form: no shell injection risk;
+  // arguments passed directly to the binary's argv.
+  //
+  // eslint-disable-next-line sonarjs/no-os-command-from-path
+  const r = spawnSync("git", ["rev-parse", "--show-toplevel"], { encoding: "utf8" });
+  if (r.status !== 0) return null;
+  return r.stdout.trim();
+}
+
+function parseArgs(argv: readonly string[]): Args | ArgError {
+  let jsonOutput = false;
+  for (let i = 0; i < argv.length; i++) {
+    const a = argv[i]!;
+    if (a === "--json") jsonOutput = true;
+    else if (a === "-h" || a === "--help") {
+      return { error: "Usage: bun tools/audit/audit-dep-currency.ts [--json]" };
+    } else {
+      return { error: `unknown argument: ${a}` };
+    }
+  }
+  const repoRoot = resolveRepoRoot();
+  if (repoRoot === null) {
+    return { error: "could not resolve repo root via 'git rev-parse --show-toplevel'" };
+  }
+  return { jsonOutput, repoRoot };
+}
+
+function walkFiles(dir: string, ext: readonly string[], skip: readonly string[]): string[] {
+  const out: string[] = [];
+  const queue: string[] = [dir];
+  while (queue.length > 0) {
+    const cur = queue.shift()!;
+    let entries: string[];
+    try {
+      entries = readdirSync(cur);
+    } catch {
+      continue;
+    }
+    for (const e of entries) {
+      if (skip.includes(e)) continue;
+      const full = join(cur, e);
+      let st;
+      try {
+        st = statSync(full);
+      } catch {
+        continue;
+      }
+      if (st.isDirectory()) {
+        queue.push(full);
+      } else if (ext.some((x) => full.endsWith(x))) {
+        out.push(full);
+      }
+    }
+  }
+  return out;
+}
+
+// (1) Scan flake.nix for nix inputs (nixpkgs.url, nix-darwin.url, etc.)
+function scanFlakeInputs(repoRoot: string): DepPin[] {
+  const pins: DepPin[] = [];
+  const flakePath = join(repoRoot, "full-ai-cluster", "flake.nix");
+  if (!existsSync(flakePath)) return pins;
+  const lines = readFileSync(flakePath, "utf8").split("\n");
+  // Match `inputName.url = "github:owner/repo/ref";`
+  // Limit alternation members to a moderate length (≤64 chars each) to
+  // avoid quadratic-blowup risk per the standard regex-safety guidance.
+  const urlRe = /^\s*(\w[\w-]{0,63})\.url\s*=\s*"([^"]{1,256})"/;
+  for (let i = 0; i < lines.length; i++) {
+    const m = urlRe.exec(lines[i]!);
+    if (m) {
+      pins.push({
+        category: "nix-input",
+        file: relative(repoRoot, flakePath),
+        line: i + 1,
+        name: m[1]!,
+        currentPin: m[2]!,
+      });
+    }
+  }
+  return pins;
+}
+
+// (2) Scan ArgoCD Application yamls for targetRevision + helm chart
+function scanArgocdApps(repoRoot: string): DepPin[] {
+  const pins: DepPin[] = [];
+  const appsDir = join(repoRoot, "full-ai-cluster", "k8s", "applications");
+  if (!existsSync(appsDir)) return pins;
+  const yamlFiles = walkFiles(appsDir, [".yaml", ".yml"], []);
+  // Anchored to start-of-line + bounded value length to avoid catastrophic
+  // backtracking; YAML values can be long but 256 chars is generous.
+  const targetRevRe = /^\s*targetRevision:\s*["']?([^"'\n]{1,256})["']?\s*$/;
+  const chartRe = /^\s*chart:\s*["']?([\w./-]{1,128})["']?\s*$/;
+  for (const f of yamlFiles) {
+    const lines = readFileSync(f, "utf8").split("\n");
+    for (let i = 0; i < lines.length; i++) {
+      const trMatch = targetRevRe.exec(lines[i]!);
+      if (trMatch) {
+        pins.push({
+          category: "argocd-target",
+          file: relative(repoRoot, f),
+          line: i + 1,
+          name: "targetRevision",
+          currentPin: trMatch[1]!,
+        });
+      }
+      const chMatch = chartRe.exec(lines[i]!);
+      if (chMatch) {
+        pins.push({
+          category: "argocd-helm-chart",
+          file: relative(repoRoot, f),
+          line: i + 1,
+          name: "chart",
+          currentPin: chMatch[1]!,
+        });
+      }
+    }
+  }
+  return pins;
+}
+
+// (3) Scan NixOS modules + K8s manifests for `image: <repo>:<tag>`
+function scanImageTags(repoRoot: string): DepPin[] {
+  const pins: DepPin[] = [];
+  // Look across full-ai-cluster/ which is where K8s + NixOS substrate lives.
+  const root = join(repoRoot, "full-ai-cluster");
+  if (!existsSync(root)) return pins;
+  const files = walkFiles(root, [".yaml", ".yml", ".nix"], ["node_modules", ".git"]);
+  // image: registry/path:tag — bounded segment lengths to prevent quadratic
+  // alternation runs; trailing tag captured separately.
+  const imgRe = /^\s*image:\s*["']?([\w./-]{1,128}):([\w.-]{1,64})["']?\s*$/;
+  for (const f of files) {
+    const lines = readFileSync(f, "utf8").split("\n");
+    for (let i = 0; i < lines.length; i++) {
+      const m = imgRe.exec(lines[i]!);
+      if (m && !m[2]!.includes("=")) {
+        pins.push({
+          category: "image-tag",
+          file: relative(repoRoot, f),
+          line: i + 1,
+          name: m[1]!,
+          currentPin: m[2]!,
+        });
+      }
+    }
+  }
+  return pins;
+}
+
+// (4) Scan .mise.toml for runtime pins
+function scanMiseRuntimes(repoRoot: string): DepPin[] {
+  const pins: DepPin[] = [];
+  const misePath = join(repoRoot, ".mise.toml");
+  if (!existsSync(misePath)) return pins;
+  const lines = readFileSync(misePath, "utf8").split("\n");
+  // [tools] section keys: `name = "version"`.
+  // Bounded alternation lengths per regex-safety guidance.
+  const toolRe = /^\s*([\w-]{1,64})\s*=\s*"([\w.-]{1,64})"/;
+  let inToolsSection = false;
+  for (let i = 0; i < lines.length; i++) {
+    const line = lines[i]!;
+    if (/^\s*\[tools\]/.test(line)) {
+      inToolsSection = true;
+      continue;
+    }
+    if (/^\s*\[/.test(line)) {
+      inToolsSection = false;
+      continue;
+    }
+    if (!inToolsSection) continue;
+    const m = toolRe.exec(line);
+    if (m) {
+      pins.push({
+        category: "mise-runtime",
+        file: relative(repoRoot, misePath),
+        line: i + 1,
+        name: m[1]!,
+        currentPin: m[2]!,
+      });
+    }
+  }
+  return pins;
+}
+
+function renderTable(pins: readonly DepPin[]): string {
+  if (pins.length === 0) return "(no dep pins found)\n";
+  const out: string[] = [];
+  out.push("# audit-dep-currency.ts — dep-pin inventory");
+  out.push("");
+  out.push(`Total pins: ${pins.length}`);
+  out.push("");
+  // Group by category for readability.
+  const byCat = new Map<string, DepPin[]>();
+  for (const p of pins) {
+    if (!byCat.has(p.category)) byCat.set(p.category, []);
+    byCat.get(p.category)!.push(p);
+  }
+  for (const [cat, list] of [...byCat.entries()].sort((a, b) => a[0].localeCompare(b[0]))) {
+    out.push(`## ${cat} (${list.length} pin${list.length === 1 ? "" : "s"})`);
+    out.push("");
+    out.push("| File | Line | Name | Current pin |");
+    out.push("|---|---|---|---|");
+    for (const p of list) {
+      out.push(`| \`${p.file}\` | ${p.line} | \`${p.name}\` | \`${p.currentPin}\` |`);
+    }
+    out.push("");
+  }
+  return out.join("\n");
+}
+
+function main(): number {
+  const parsed = parseArgs(process.argv.slice(2));
+  if ("error" in parsed) {
+    process.stderr.write(`audit-dep-currency: ${parsed.error}\n`);
+    return 1;
+  }
+  const { jsonOutput, repoRoot } = parsed;
+  const pins: DepPin[] = [
+    ...scanFlakeInputs(repoRoot),
+    ...scanArgocdApps(repoRoot),
+    ...scanImageTags(repoRoot),
+    ...scanMiseRuntimes(repoRoot),
+  ];
+  if (jsonOutput) {
+    process.stdout.write(JSON.stringify({ count: pins.length, pins }, null, 2) + "\n");
+  } else {
+    process.stdout.write(renderTable(pins));
+  }
+  return 0;
+}
+
+process.exit(main());