diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7158dac..f82e068 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 
 ### Added
+- **`skill-seekers doctor` command** — 8 diagnostic checks (Python version, package install, git, core/optional deps, API keys, MCP server, output dir) with pass/warn/fail status and `--verbose` flag (#316)
 - **Prompt injection check workflow** — bundled `prompt-injection-check` workflow scans scraped content for injection patterns (role assumption, instruction overrides, delimiter injection, hidden instructions). Added as first stage in `default` and `security-focus` workflows. Flags suspicious content without removing it (#324)
 - **6 behavioral UML diagrams** — 3 sequence (create pipeline, GitHub+C3.x flow, MCP invocation), 2 activity (source detection, enhancement pipeline), 1 component (runtime dependencies with interface contracts)
 
diff --git a/pyproject.toml b/pyproject.toml
index 655e344..479f179 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -299,6 +299,7 @@ skill-seekers = "skill_seekers.cli.main:main"
 
 # Individual tool entry points
 skill-seekers-create = "skill_seekers.cli.create_command:main"  # NEW: Unified create command
+skill-seekers-doctor = "skill_seekers.cli.doctor:main"
 skill-seekers-config = "skill_seekers.cli.config_command:main"
 skill-seekers-resume = "skill_seekers.cli.resume_command:main"
 skill-seekers-scrape = "skill_seekers.cli.doc_scraper:main"
diff --git a/src/skill_seekers/cli/doctor.py b/src/skill_seekers/cli/doctor.py
new file mode 100644
index 0000000..6bac5a9
--- /dev/null
+++ b/src/skill_seekers/cli/doctor.py
@@ -0,0 +1,303 @@
+"""
+skill-seekers doctor — Environment health check command.
+
+Runs 8 quick offline checks and prints a diagnostic summary,
+similar to `brew doctor` or `flutter doctor`.
+"""
+
+from __future__ import annotations
+
+import argparse
+import os
+import shutil
+import subprocess
+import sys
+from dataclasses import dataclass
+from typing import Literal
+
+
+@dataclass
+class CheckResult:
+    """Result of a single health check."""
+
+    name: str
+    status: Literal["pass", "warn", "fail"]
+    detail: str
+    critical: bool = False
+    verbose_detail: str = ""
+
+
+# ── Core dependency import names (from pyproject.toml dependencies) ──────────
+CORE_DEPS = {
+    "requests": "requests",
+    "beautifulsoup4": "bs4",
+    "PyGithub": "github",
+    "GitPython": "git",
+    "httpx": "httpx",
+    "anthropic": "anthropic",
+    "PyMuPDF": "fitz",
+    "Pillow": "PIL",
+    "pydantic": "pydantic",
+    "pydantic-settings": "pydantic_settings",
+    "python-dotenv": "dotenv",
+    "jsonschema": "jsonschema",
+    "click": "click",
+    "Pygments": "pygments",
+}
+
+# ── Optional dependency import names ─────────────────────────────────────────
+OPTIONAL_DEPS = {
+    "mammoth": "mammoth",
+    "ebooklib": "ebooklib",
+    "yt-dlp": "yt_dlp",
+    "mcp": "mcp",
+    "google-generativeai": "google.generativeai",
+    "openai": "openai",
+    "chromadb": "chromadb",
+    "weaviate-client": "weaviate",
+    "nbformat": "nbformat",
+    "feedparser": "feedparser",
+}
+
+# ── API keys to check ────────────────────────────────────────────────────────
+API_KEYS = ["ANTHROPIC_API_KEY", "GITHUB_TOKEN", "GOOGLE_API_KEY", "OPENAI_API_KEY"]
+
+
+def _try_import(module_name: str) -> tuple[bool, str]:
+    """Try to import a module and return (success, version_or_error)."""
+    try:
+        mod = __import__(module_name.split(".")[0])
+        version = getattr(mod, "__version__", getattr(mod, "VERSION", "installed"))
+        return True, str(version)
+    except Exception as e:
+        return False, str(e)
+
+
+def check_python_version() -> CheckResult:
+    """Check 1: Python version >= 3.10."""
+    v = sys.version_info
+    version_str = f"{v.major}.{v.minor}.{v.micro}"
+    if v >= (3, 10):
+        return CheckResult("Python version", "pass", version_str, critical=True)
+    return CheckResult("Python version", "fail", f"{version_str} (requires 3.10+)", critical=True)
+
+
+def check_package_installed() -> CheckResult:
+    """Check 2: skill-seekers package importable with version."""
+    try:
+        from skill_seekers._version import __version__
+
+        return CheckResult("skill-seekers installed", "pass", f"v{__version__}", critical=True)
+    except ImportError:
+        return CheckResult(
+            "skill-seekers installed", "fail", "Cannot import skill_seekers", critical=True
+        )
+
+
+def check_git() -> CheckResult:
+    """Check 3: git available in PATH."""
+    git_path = shutil.which("git")
+    if not git_path:
+        return CheckResult("Git", "warn", "git not found in PATH")
+    try:
+        result = subprocess.run(["git", "--version"], capture_output=True, text=True, timeout=5)
+        version = result.stdout.strip()
+        return CheckResult("Git", "pass", version, verbose_detail=f"Path: {git_path}")
+    except Exception as e:
+        return CheckResult("Git", "warn", f"git found but error: {e}")
+
+
+def check_core_deps() -> CheckResult:
+    """Check 4: Core dependencies importable."""
+    found = []
+    missing = []
+    details = []
+    for pkg_name, import_name in CORE_DEPS.items():
+        ok, info = _try_import(import_name)
+        if ok:
+            found.append(pkg_name)
+            details.append(f"  {pkg_name}: {info}")
+        else:
+            missing.append(pkg_name)
+            details.append(f"  {pkg_name}: MISSING")
+
+    if not missing:
+        return CheckResult(
+            "Core dependencies",
+            "pass",
+            f"All {len(found)} found",
+            critical=True,
+            verbose_detail="\n".join(details),
+        )
+    return CheckResult(
+        "Core dependencies",
+        "fail",
+        f"{len(missing)} missing: {', '.join(missing)}",
+        critical=True,
+        verbose_detail="\n".join(details),
+    )
+
+
+def check_optional_deps() -> CheckResult:
+    """Check 5: Optional dependencies status."""
+    found = []
+    missing = []
+    details = []
+    for pkg_name, import_name in OPTIONAL_DEPS.items():
+        ok, info = _try_import(import_name)
+        if ok:
+            found.append(pkg_name)
+            details.append(f"  {pkg_name}: {info}")
+        else:
+            missing.append(pkg_name)
+            details.append(f"  {pkg_name}: not installed")
+
+    total = len(OPTIONAL_DEPS)
+    if not missing:
+        return CheckResult(
+            "Optional dependencies",
+            "pass",
+            f"{total}/{total} installed",
+            verbose_detail="\n".join(details),
+        )
+    return CheckResult(
+        "Optional dependencies",
+        "warn",
+        f"{len(found)}/{total} installed (not installed: {', '.join(missing)})",
+        verbose_detail="\n".join(details),
+    )
+
+
+def check_api_keys() -> CheckResult:
+    """Check 6: API keys set in environment."""
+    set_keys = []
+    missing_keys = []
+    details = []
+    for key in API_KEYS:
+        val = os.environ.get(key)
+        if val:
+            set_keys.append(key)
+            masked = val[:4] + "..." + val[-4:] if len(val) > 12 else "***"
+            details.append(f"  {key}: {masked}")
+        else:
+            missing_keys.append(key)
+            details.append(f"  {key}: not set")
+
+    if not missing_keys:
+        return CheckResult(
+            "API keys",
+            "pass",
+            f"All {len(API_KEYS)} set",
+            verbose_detail="\n".join(details),
+        )
+    if set_keys:
+        return CheckResult(
+            "API keys",
+            "warn",
+            f"{len(set_keys)} set ({', '.join(missing_keys)} not set)",
+            verbose_detail="\n".join(details),
+        )
+    return CheckResult(
+        "API keys",
+        "warn",
+        "None set (enhancement features will use LOCAL mode)",
+        verbose_detail="\n".join(details),
+    )
+
+
+def check_mcp_server() -> CheckResult:
+    """Check 7: MCP server module importable."""
+    try:
+        from skill_seekers.mcp import server_fastmcp  # noqa: F401
+
+        return CheckResult("MCP server", "pass", "Importable")
+    except ImportError as e:
+        return CheckResult("MCP server", "warn", f"Not available ({e})")
+    except Exception as e:
+        return CheckResult("MCP server", "warn", f"Import error: {e}")
+
+
+def check_output_directory() -> CheckResult:
+    """Check 8: Current directory is writable."""
+    cwd = os.getcwd()
+    if os.access(cwd, os.W_OK):
+        return CheckResult("Output directory", "pass", f"{cwd} (writable)", critical=True)
+    return CheckResult("Output directory", "fail", f"{cwd} (NOT writable)", critical=True)
+
+
+def run_all_checks() -> list[CheckResult]:
+    """Run all 8 health checks and return results."""
+    return [
+        check_python_version(),
+        check_package_installed(),
+        check_git(),
+        check_core_deps(),
+        check_optional_deps(),
+        check_api_keys(),
+        check_mcp_server(),
+        check_output_directory(),
+    ]
+
+
+STATUS_ICONS = {"pass": "\u2705", "warn": "\u26a0\ufe0f ", "fail": "\u274c"}
+
+
+def print_report(results: list[CheckResult], verbose: bool = False) -> int:
+    """Print formatted report and return exit code."""
+    try:
+        from skill_seekers._version import __version__
+
+        version = __version__
+    except ImportError:
+        version = "unknown"
+
+    print()
+    print("=" * 50)
+    print(f"  Skill Seekers Doctor (v{version})")
+    print("=" * 50)
+    print()
+
+    for r in results:
+        icon = STATUS_ICONS[r.status]
+        print(f"  {icon} {r.name} — {r.detail}")
+        if verbose and r.verbose_detail:
+            for line in r.verbose_detail.split("\n"):
+                print(f"      {line}")
+
+    passed = sum(1 for r in results if r.status == "pass")
+    warnings = sum(1 for r in results if r.status == "warn")
+    errors = sum(1 for r in results if r.status == "fail")
+
+    print()
+    print("-" * 50)
+    print(f"  {passed} passed, {warnings} warnings, {errors} errors")
+
+    if errors == 0:
+        if warnings > 0:
+            print("  All critical checks passed with some warnings.")
+        else:
+            print("  All checks passed!")
+    else:
+        print("  Some critical checks failed. Fix errors above.")
+
+    print()
+    return 1 if errors > 0 else 0
+
+
+def main() -> int:
+    """Entry point for doctor command."""
+    parser = argparse.ArgumentParser(
+        prog="skill-seekers doctor",
+        description="Check environment health and dependencies",
+    )
+    parser.add_argument(
+        "--verbose", "-v", action="store_true", help="Show detailed diagnostic info"
+    )
+    args = parser.parse_args()
+
+    results = run_all_checks()
+    return print_report(results, verbose=args.verbose)
+
+
+if __name__ == "__main__":
+    sys.exit(main())
diff --git a/src/skill_seekers/cli/main.py b/src/skill_seekers/cli/main.py
index f33c38e..e46f9e5 100644
--- a/src/skill_seekers/cli/main.py
+++ b/src/skill_seekers/cli/main.py
@@ -56,6 +56,7 @@ from skill_seekers.cli import __version__
 # Command module mapping (command name -> module path)
 COMMAND_MODULES = {
     "create": "skill_seekers.cli.create_command",  # NEW: Unified create command
+    "doctor": "skill_seekers.cli.doctor",
     "config": "skill_seekers.cli.config_command",
     "scrape": "skill_seekers.cli.doc_scraper",
     "github": "skill_seekers.cli.github_scraper",
diff --git a/src/skill_seekers/cli/parsers/__init__.py b/src/skill_seekers/cli/parsers/__init__.py
index ddf04ee..d5faaef 100644
--- a/src/skill_seekers/cli/parsers/__init__.py
+++ b/src/skill_seekers/cli/parsers/__init__.py
@@ -32,6 +32,7 @@ from .multilang_parser import MultilangParser
 from .quality_parser import QualityParser
 from .workflows_parser import WorkflowsParser
 from .sync_config_parser import SyncConfigParser
+from .doctor_parser import DoctorParser
 
 # New source type parsers (v3.2.0+)
 from .jupyter_parser import JupyterParser
@@ -48,6 +49,7 @@ from .chat_parser import ChatParser
 # Registry of all parsers (in order of usage frequency)
 PARSERS = [
     CreateParser(),  # NEW: Unified create command (placed first for prominence)
+    DoctorParser(),
     ConfigParser(),
     ScrapeParser(),
     GitHubParser(),
diff --git a/src/skill_seekers/cli/parsers/doctor_parser.py b/src/skill_seekers/cli/parsers/doctor_parser.py
new file mode 100644
index 0000000..5edad00
--- /dev/null
+++ b/src/skill_seekers/cli/parsers/doctor_parser.py
@@ -0,0 +1,25 @@
+"""Doctor subcommand parser."""
+
+from .base import SubcommandParser
+
+
+class DoctorParser(SubcommandParser):
+    """Parser for doctor subcommand."""
+
+    @property
+    def name(self) -> str:
+        return "doctor"
+
+    @property
+    def help(self) -> str:
+        return "Check environment health and dependencies"
+
+    @property
+    def description(self) -> str:
+        return "Run diagnostic checks on Python version, dependencies, API keys, and more"
+
+    def add_arguments(self, parser):
+        """Add doctor-specific arguments."""
+        parser.add_argument(
+            "--verbose", "-v", action="store_true", help="Show detailed diagnostic info"
+        )
diff --git a/tests/test_doctor.py b/tests/test_doctor.py
new file mode 100644
index 0000000..e8ac14b
--- /dev/null
+++ b/tests/test_doctor.py
@@ -0,0 +1,164 @@
+"""Tests for skill-seekers doctor command (#316)."""
+
+from __future__ import annotations
+
+import os
+from unittest.mock import patch
+
+from skill_seekers.cli.doctor import (
+    CheckResult,
+    check_api_keys,
+    check_core_deps,
+    check_git,
+    check_mcp_server,
+    check_optional_deps,
+    check_output_directory,
+    check_package_installed,
+    check_python_version,
+    print_report,
+    run_all_checks,
+)
+
+
+class TestCheckPythonVersion:
+    def test_passes_on_current_python(self):
+        result = check_python_version()
+        assert result.status == "pass"
+        assert result.critical is True
+
+    def test_detail_contains_version(self):
+        result = check_python_version()
+        assert "." in result.detail  # e.g. "3.14.3"
+
+
+class TestCheckPackageInstalled:
+    def test_passes_when_installed(self):
+        result = check_package_installed()
+        assert result.status == "pass"
+        assert result.detail.startswith("v")
+
+    def test_fails_when_import_broken(self):
+        with (
+            patch.dict("sys.modules", {"skill_seekers._version": None}),
+            patch("builtins.__import__", side_effect=ImportError("mocked")),
+        ):
+            result = check_package_installed()
+            assert result.status == "fail"
+
+
+class TestCheckGit:
+    def test_passes_when_git_available(self):
+        result = check_git()
+        # Most CI/dev environments have git
+        assert result.status in ("pass", "warn")
+
+    def test_warns_when_git_missing(self):
+        with patch("skill_seekers.cli.doctor.shutil.which", return_value=None):
+            result = check_git()
+            assert result.status == "warn"
+
+
+class TestCheckCoreDeps:
+    def test_passes_in_normal_environment(self):
+        result = check_core_deps()
+        assert result.status == "pass"
+        assert result.critical is True
+
+    def test_detail_shows_count(self):
+        result = check_core_deps()
+        assert "found" in result.detail.lower() or "missing" in result.detail.lower()
+
+
+class TestCheckOptionalDeps:
+    def test_returns_result(self):
+        result = check_optional_deps()
+        assert result.status in ("pass", "warn")
+        assert "/" in result.detail  # e.g. "7/10 installed"
+
+
+class TestCheckApiKeys:
+    def test_warns_when_no_keys(self):
+        with patch.dict(os.environ, {}, clear=True):
+            result = check_api_keys()
+            assert result.status == "warn"
+
+    def test_passes_when_all_set(self):
+        env = {
+            "ANTHROPIC_API_KEY": "sk-ant-test123456789",
+            "GITHUB_TOKEN": "ghp_test123456789",
+            "GOOGLE_API_KEY": "AIza_test123456789",
+            "OPENAI_API_KEY": "sk-test123456789",
+        }
+        with patch.dict(os.environ, env, clear=True):
+            result = check_api_keys()
+            assert result.status == "pass"
+
+    def test_partial_keys_warns(self):
+        env = {"ANTHROPIC_API_KEY": "sk-ant-test123456789"}
+        with patch.dict(os.environ, env, clear=True):
+            result = check_api_keys()
+            assert result.status == "warn"
+            assert "1 set" in result.detail
+
+
+class TestCheckMcpServer:
+    def test_returns_result(self):
+        result = check_mcp_server()
+        assert result.status in ("pass", "warn")
+
+
+class TestCheckOutputDirectory:
+    def test_passes_in_writable_dir(self):
+        result = check_output_directory()
+        assert result.status == "pass"
+        assert result.critical is True
+
+
+class TestRunAllChecks:
+    def test_returns_8_results(self):
+        results = run_all_checks()
+        assert len(results) == 8
+
+    def test_all_have_name_and_status(self):
+        results = run_all_checks()
+        for r in results:
+            assert isinstance(r, CheckResult)
+            assert r.name
+            assert r.status in ("pass", "warn", "fail")
+
+
+class TestPrintReport:
+    def test_returns_0_when_no_failures(self, capsys):
+        results = [
+            CheckResult("Test1", "pass", "ok", critical=True),
+            CheckResult("Test2", "warn", "meh"),
+        ]
+        code = print_report(results)
+        assert code == 0
+        captured = capsys.readouterr()
+        assert "1 passed" in captured.out
+        assert "1 warnings" in captured.out
+
+    def test_returns_1_when_critical_failure(self, capsys):
+        results = [
+            CheckResult("Test1", "pass", "ok"),
+            CheckResult("Test2", "fail", "broken", critical=True),
+        ]
+        code = print_report(results)
+        assert code == 1
+
+    def test_verbose_shows_detail(self, capsys):
+        results = [
+            CheckResult("Test1", "pass", "ok", verbose_detail="  extra: info"),
+        ]
+        print_report(results, verbose=True)
+        captured = capsys.readouterr()
+        assert "extra: info" in captured.out
+
+    def test_no_verbose_hides_detail(self, capsys):
+        results = [
+            CheckResult("Test1", "pass", "ok", verbose_detail="  secret: hidden"),
+        ]
+        print_report(results, verbose=False)
+        captured = capsys.readouterr()
+        assert "secret: hidden" not in captured.out