diff --git a/extensions/catalog.json b/extensions/catalog.json
index fed3f08842..4194e8084d 100644
--- a/extensions/catalog.json
+++ b/extensions/catalog.json
@@ -51,7 +51,7 @@
     "git": {
       "name": "Git Branching Workflow",
       "id": "git",
-      "version": "1.0.1",
+      "version": "1.0.2",
       "description": "Feature branch creation, numbering (sequential/timestamp), validation, and Git remote detection",
       "author": "spec-kit-core",
       "repository": "https://github.com/github/spec-kit",
diff --git a/extensions/git/extension.yml b/extensions/git/extension.yml
index 90a7e56769..2d762a126a 100644
--- a/extensions/git/extension.yml
+++ b/extensions/git/extension.yml
@@ -3,7 +3,7 @@ schema_version: "1.0"
 extension:
   id: git
   name: "Git Branching Workflow"
-  version: "1.0.1"
+  version: "1.0.2"
   description: "Feature branch creation, numbering (sequential/timestamp), templating, validation, and Git remote detection"
   author: spec-kit-core
   repository: https://github.com/github/spec-kit
diff --git a/extensions/git/scripts/bash/create-new-feature-branch.sh b/extensions/git/scripts/bash/create-new-feature-branch.sh
index 5303bb97c9..3b19edc4bc 100755
--- a/extensions/git/scripts/bash/create-new-feature-branch.sh
+++ b/extensions/git/scripts/bash/create-new-feature-branch.sh
@@ -191,7 +191,10 @@ check_existing_branches() {
             highest_branch=$highest_remote
         fi
     else
-        git fetch --all --prune >/dev/null 2>&1 || true
+        # The dry-run path already sets this for `git ls-remote`. Without it,
+        # an HTTPS remote with no usable credential helper makes git prompt on
+        # the tty, and /speckit.specify hangs instead of continuing.
+        GIT_TERMINAL_PROMPT=0 git fetch --all --prune >/dev/null 2>&1 || true
         local highest_branch=$(get_highest_from_branches "$scope_prefix")
     fi
 
diff --git a/extensions/git/scripts/powershell/create-new-feature-branch.ps1 b/extensions/git/scripts/powershell/create-new-feature-branch.ps1
index 4d06a113a4..b97a1cc9c2 100644
--- a/extensions/git/scripts/powershell/create-new-feature-branch.ps1
+++ b/extensions/git/scripts/powershell/create-new-feature-branch.ps1
@@ -162,9 +162,13 @@ function Get-NextBranchNumber {
         $highestRemote = Get-HighestNumberFromRemoteRefs -ScopePrefix $ScopePrefix
         $highestBranch = [Math]::Max($highestBranch, $highestRemote)
     } else {
+        # Mirror the ls-remote guard: an HTTPS remote without a credential
+        # helper would otherwise prompt on the tty and block the caller.
+        $env:GIT_TERMINAL_PROMPT = '0'
         try {
             git fetch --all --prune 2>$null | Out-Null
         } catch { }
+        $env:GIT_TERMINAL_PROMPT = $null
         $highestBranch = Get-HighestNumberFromBranches -ScopePrefix $ScopePrefix
     }
 
diff --git a/extensions/git/scripts/python/create_new_feature_branch.py b/extensions/git/scripts/python/create_new_feature_branch.py
index 202b1f796e..dd95a10338 100644
--- a/extensions/git/scripts/python/create_new_feature_branch.py
+++ b/extensions/git/scripts/python/create_new_feature_branch.py
@@ -266,11 +266,15 @@ def check_existing_branches(
             get_highest_from_branches(repo_root, scope_prefix),
         )
     else:
+        # The dry-run path already passes GIT_TERMINAL_PROMPT=0 to ls-remote.
+        # Without it here, an HTTPS remote with no usable credential helper
+        # prompts on the tty and /speckit.specify hangs instead of continuing.
         subprocess.run(
             ["git", "fetch", "--all", "--prune"],
             cwd=repo_root,
             capture_output=True,
             text=True,
+            env={**os.environ, "GIT_TERMINAL_PROMPT": "0"},
         )
         highest_branch = get_highest_from_branches(repo_root, scope_prefix)
 
diff --git a/tests/test_git_fetch_prompt_guard.py b/tests/test_git_fetch_prompt_guard.py
new file mode 100644
index 0000000000..03dd9b0791
--- /dev/null
+++ b/tests/test_git_fetch_prompt_guard.py
@@ -0,0 +1,166 @@
+"""Regression tests for the git extension's feature-branch fetch guard (#5199).
+
+`check_existing_branches` runs `git fetch --all --prune` for non-dry-run
+invocations. Without ``GIT_TERMINAL_PROMPT=0`` an HTTPS remote that has no
+usable credential helper makes git prompt on the tty, so the mandatory
+``before_specify`` hook (and therefore ``/speckit.specify``) blocks instead of
+continuing. The dry-run path already guarded ``git ls-remote``; these tests pin
+the same guard on the real fetch path in all three implementations.
+"""
+
+import importlib.util
+import os
+import shutil
+import subprocess
+import sys
+from pathlib import Path
+
+import pytest
+
+from tests.conftest import requires_bash
+
+PROJECT_ROOT = Path(__file__).resolve().parent.parent
+EXT_SCRIPTS = PROJECT_ROOT / "extensions" / "git" / "scripts"
+PY_SCRIPT = EXT_SCRIPTS / "python" / "create_new_feature_branch.py"
+BASH_SCRIPT = EXT_SCRIPTS / "bash" / "create-new-feature-branch.sh"
+PS1_SCRIPT = EXT_SCRIPTS / "powershell" / "create-new-feature-branch.ps1"
+
+HAS_PWSH = shutil.which("pwsh") is not None
+
+
+def _load_python_script():
+    spec = importlib.util.spec_from_file_location(
+        "ext_create_new_feature_branch", PY_SCRIPT
+    )
+    assert spec is not None and spec.loader is not None
+    module = importlib.util.module_from_spec(spec)
+    # dataclasses resolves annotations through sys.modules[cls.__module__].
+    sys.modules[spec.name] = module
+    spec.loader.exec_module(module)
+    return module
+
+
+def _init_repo(path: Path) -> None:
+    subprocess.run(["git", "init", "-q"], cwd=path, check=True)
+    subprocess.run(
+        ["git", "config", "user.email", "test@example.com"], cwd=path, check=True
+    )
+    subprocess.run(["git", "config", "user.name", "Test User"], cwd=path, check=True)
+
+
+def _run(command, cwd: Path, log: Path):
+    env = {**os.environ, "STUB_LOG": str(log)}
+    env.pop("GIT_TERMINAL_PROMPT", None)
+    return subprocess.run(command, cwd=cwd, env=env, capture_output=True, text=True)
+
+
+def test_python_fetch_disables_terminal_prompt(tmp_path, monkeypatch):
+    module = _load_python_script()
+    specs_dir = tmp_path / "specs"
+    specs_dir.mkdir()
+
+    calls = []
+
+    class _Result:
+        returncode = 0
+        stdout = ""
+        stderr = ""
+
+    def fake_run(cmd, **kwargs):
+        calls.append((list(cmd), kwargs))
+        return _Result()
+
+    monkeypatch.setattr(module.subprocess, "run", fake_run)
+    module.check_existing_branches(tmp_path, specs_dir, False, "")
+
+    fetch_calls = [call for call in calls if call[0][:2] == ["git", "fetch"]]
+    assert len(fetch_calls) == 1, calls
+    assert fetch_calls[0][1]["env"]["GIT_TERMINAL_PROMPT"] == "0"
+
+
+def _install_scripts(repo: Path) -> Path:
+    """Install the extension scripts inside the temp project.
+
+    The scripts resolve their project root from their own location, so running
+    the checkout's copy would make them create a branch in this repository
+    instead of the temp project.
+
+    Args:
+        repo: Temporary project root.
+
+    Returns:
+        The temp project root, with ``.specify/scripts`` populated.
+    """
+    layout = {
+        "bash": (
+            PROJECT_ROOT / "scripts" / "bash" / "common.sh",
+            EXT_SCRIPTS / "bash" / "git-common.sh",
+            EXT_SCRIPTS / "bash" / "create-new-feature-branch.sh",
+        ),
+        "powershell": (
+            PROJECT_ROOT / "scripts" / "powershell" / "common.ps1",
+            EXT_SCRIPTS / "powershell" / "git-common.ps1",
+            EXT_SCRIPTS / "powershell" / "create-new-feature-branch.ps1",
+        ),
+        "python": (PROJECT_ROOT / "scripts" / "python" / "common.py",),
+    }
+    for flavor, sources in layout.items():
+        target = repo / ".specify" / "scripts" / flavor
+        target.mkdir(parents=True)
+        for source in sources:
+            if source.is_file():
+                shutil.copy(source, target / source.name)
+    return repo
+
+
+@requires_bash
+def test_bash_fetch_disables_terminal_prompt(tmp_path):
+    _init_repo(tmp_path)
+    _install_scripts(tmp_path)
+    script = tmp_path / ".specify" / "scripts" / "bash" / "create-new-feature-branch.sh"
+    log = tmp_path / "prompt.log"
+    harness = tmp_path / "harness.sh"
+    harness.write_text(
+        "#!/usr/bin/env bash\n"
+        "git() {\n"
+        '  if [ "$1" = fetch ]; then\n'
+        '    printf \'%s\' "${GIT_TERMINAL_PROMPT-<unset>}" > "$STUB_LOG"\n'
+        "    return 0\n"
+        "  fi\n"
+        '  command git "$@"\n'
+        "}\n"
+        "export -f git\n"
+        f'exec bash "{script.as_posix()}" --short-name probe-fetch-guard "fetch guard"\n',
+        encoding="utf-8",
+    )
+
+    _run(["bash", harness.as_posix()], cwd=tmp_path, log=log)
+
+    assert log.read_text(encoding="utf-8") == "0"
+
+
+@pytest.mark.skipif(not HAS_PWSH, reason="pwsh is not available")
+def test_powershell_fetch_disables_terminal_prompt(tmp_path):
+    _init_repo(tmp_path)
+    _install_scripts(tmp_path)
+    script = (
+        tmp_path / ".specify" / "scripts" / "powershell" / "create-new-feature-branch.ps1"
+    )
+    log = tmp_path / "prompt.log"
+    harness = tmp_path / "harness.ps1"
+    harness.write_text(
+        "function git {\n"
+        "  if ($args[0] -eq 'fetch') {\n"
+        f"    Set-Content -NoNewline -Path '{log}' -Value \"$($env:GIT_TERMINAL_PROMPT)\"\n"
+        "    return\n"
+        "  }\n"
+        "  $real = (Get-Command git.exe -CommandType Application).Source\n"
+        "  & $real @args\n"
+        "}\n"
+        f". '{script}' -ShortName 'probe-fetch-guard' 'fetch guard'\n",
+        encoding="utf-8",
+    )
+
+    _run(["pwsh", "-NoProfile", "-File", str(harness)], cwd=tmp_path, log=log)
+
+    assert log.read_text(encoding="utf-8") == "0"