diff --git a/src/afk/agents/prompts/store.py b/src/afk/agents/prompts/store.py
index 90c6615..c86e617 100644
--- a/src/afk/agents/prompts/store.py
+++ b/src/afk/agents/prompts/store.py
@@ -102,6 +102,9 @@ def resolve_prompt_file_path(
 ) -> Path:
     """
     Resolve the target prompt file path with root-constrained access checks.
+
+    Absolute paths bypass the security check but still require the file to exist.
+    Relative paths are resolved against prompt_root and checked for directory escape.
     """
     if instruction_file is not None:
         candidate = Path(instruction_file)
@@ -110,7 +113,18 @@ def resolve_prompt_file_path(
         candidate = Path(derive_auto_prompt_filename(agent_name))
         source = "auto_prompt"
 
-    target = candidate if candidate.is_absolute() else (prompt_root / candidate)
+    # Absolute paths bypass security check but must exist
+    if candidate.is_absolute():
+        resolved = candidate.resolve()
+        if not resolved.exists() or not resolved.is_file():
+            raise PromptResolutionError(
+                f"prompt file not found for {source} "
+                f"(path='{resolved}')"
+            )
+        return resolved
+
+    # Relative paths: resolve against root and check for escape
+    target = prompt_root / candidate
     resolved = target.resolve()
     if not _is_under(resolved, prompt_root):
         raise PromptAccessError(
diff --git a/tests/agents/test_prompt_loader.py b/tests/agents/test_prompt_loader.py
index a1ce004..0c274f0 100644
--- a/tests/agents/test_prompt_loader.py
+++ b/tests/agents/test_prompt_loader.py
@@ -141,6 +141,42 @@ def test_prompt_path_escape_raises_access_error(tmp_path: Path):
         run_async(agent.resolve_instructions({}))
 
 
+def test_absolute_path_bypasses_security_check(tmp_path: Path):
+    """Absolute paths should bypass security check but still require file to exist."""
+    from afk.agents.prompts.store import resolve_prompts_dir
+
+    root = tmp_path / "prompts"
+    root.mkdir(parents=True, exist_ok=True)
+
+    # Create absolute path to existing file
+    valid_file = root / "valid.md"
+    valid_file.write_text("valid content", encoding="utf-8")
+    abs_path = valid_file.resolve()
+
+    # Get prompt root for context
+    prompt_root = resolve_prompts_dir(prompts_dir=None, cwd=tmp_path)
+
+    # Import directly - this is a module-level function
+    from afk.agents.prompts.store import resolve_prompt_file_path
+
+    # Should work - absolute path bypasses security check
+    resolved = resolve_prompt_file_path(
+        prompt_root=prompt_root,
+        instruction_file=abs_path,
+        agent_name="test",
+    )
+    assert resolved == abs_path
+
+    # Non-existent absolute path should fail with PromptResolutionError (not access error)
+    non_existent = Path("/nonexistent/file.txt")
+    with pytest.raises(PromptResolutionError):
+        resolve_prompt_file_path(
+            prompt_root=prompt_root,
+            instruction_file=non_existent,
+            agent_name="test",
+        )
+
+
 def test_prompt_template_renders_context_and_reserved_keys(tmp_path: Path):
     root = tmp_path / "prompts"
     _write_prompt(
diff --git a/tests/test_config.py b/tests/test_config.py
new file mode 100644
index 0000000..a028f9c
--- /dev/null
+++ b/tests/test_config.py
@@ -0,0 +1,293 @@
+"""
+Tests for the centralized config module.
+"""
+
+from __future__ import annotations
+
+import pytest
+
+from afk.config import (
+    MCPServerEnv,
+    MemoryEnv,
+    RunnerEnv,
+    Settings,
+    EnvVarField,
+    _bool,
+    _csv_list,
+    _float,
+    _int,
+)
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+
+class FakeSettings(Settings):
+    """Minimal Settings subclass for testing the base class."""
+
+    STR_VAL: ClassVar[str] = EnvVarField("FAKE_STR", default="default_str")
+    INT_VAL: ClassVar[int] = EnvVarField("FAKE_INT", default=42, parser=_int)
+    FLOAT_VAL: ClassVar[float] = EnvVarField("FAKE_FLOAT", default=1.5, parser=_float)
+    BOOL_VAL: ClassVar[bool] = EnvVarField("FAKE_BOOL", default=False, parser=_bool)
+    LIST_VAL: ClassVar[list[str]] = EnvVarField(
+        "FAKE_LIST", default=[], parser=_csv_list
+    )
+    NONE_STR: ClassVar[str] = EnvVarField("FAKE_NONE", default=None)
+
+
+# ---------------------------------------------------------------------------
+# Parser unit tests
+# ---------------------------------------------------------------------------
+
+
+class TestParsers:
+    @pytest.mark.parametrize(
+        "raw,expected",
+        [
+            ("1", True),
+            ("true", True),
+            ("True", True),
+            ("yes", True),
+            ("y", True),
+            ("on", True),
+            ("0", False),
+            ("false", False),
+            ("no", False),
+            ("off", False),
+        ],
+    )
+    def test_bool_parses_valid_values(self, raw, expected):
+        assert _bool(raw) == expected
+
+    @pytest.mark.parametrize("raw", ["maybe", "2", "tru", "yeah", ""])
+    def test_bool_raises_on_invalid_input(self, raw):
+        with pytest.raises(ValueError, match="Invalid boolean"):
+            _bool(raw)
+
+    @pytest.mark.parametrize(
+        "raw,expected",
+        [
+            ("a,b,c", ["a", "b", "c"]),
+            ("a, b , c", ["a", "b", "c"]),
+            ("one", ["one"]),
+            ("a,b,,c", ["a", "b", "c"]),
+            ("", []),
+            ("  ", []),
+        ],
+    )
+    def test_csv_list_parses_valid_input(self, raw, expected):
+        assert _csv_list(raw) == expected
+
+    def test_int_parses_valid_input(self):
+        assert _int("123") == 123
+        assert _int("-456") == -456
+
+    def test_int_raises_on_invalid_input(self):
+        with pytest.raises(ValueError):
+            _int("not_a_number")
+
+    def test_float_parses_valid_input(self):
+        assert _float("1.5") == 1.5
+        assert _float("-0.25") == -0.25
+
+    def test_float_raises_on_invalid_input(self):
+        with pytest.raises(ValueError):
+            _float("not_a_float")
+
+
+# ---------------------------------------------------------------------------
+# Settings.from_env() tests
+# ---------------------------------------------------------------------------
+
+
+class TestSettingsFromEnv:
+    def test_missing_env_vars_use_defaults(self, monkeypatch):
+        # Ensure none of the env vars are set
+        for var in (
+            "FAKE_STR",
+            "FAKE_INT",
+            "FAKE_FLOAT",
+            "FAKE_BOOL",
+            "FAKE_LIST",
+            "FAKE_NONE",
+        ):
+            monkeypatch.delenv(var, raising=False)
+
+        settings = FakeSettings.from_env()
+        assert settings.STR_VAL == "default_str"
+        assert settings.INT_VAL == 42
+        assert settings.FLOAT_VAL == 1.5
+        assert settings.BOOL_VAL is False
+        assert settings.LIST_VAL == []
+        assert settings.NONE_STR is None
+
+    def test_env_vars_override_defaults(self, monkeypatch):
+        monkeypatch.setenv("FAKE_STR", "from_env")
+        monkeypatch.setenv("FAKE_INT", "100")
+        monkeypatch.setenv("FAKE_FLOAT", "2.5")
+        monkeypatch.setenv("FAKE_BOOL", "true")
+        monkeypatch.setenv("FAKE_LIST", "a,b,c")
+        monkeypatch.setenv("FAKE_NONE", "non_none")
+
+        settings = FakeSettings.from_env()
+        assert settings.STR_VAL == "from_env"
+        assert settings.INT_VAL == 100
+        assert settings.FLOAT_VAL == 2.5
+        assert settings.BOOL_VAL is True
+        assert settings.LIST_VAL == ["a", "b", "c"]
+        assert settings.NONE_STR == "non_none"
+
+    def test_empty_string_env_var_falls_back_to_default(self, monkeypatch):
+        monkeypatch.setenv("FAKE_STR", "")
+        monkeypatch.setenv("FAKE_INT", "")
+        monkeypatch.setenv("FAKE_LIST", "")
+
+        settings = FakeSettings.from_env()
+        assert settings.STR_VAL == "default_str"
+        assert settings.INT_VAL == 42
+        assert settings.LIST_VAL == []
+
+    def test_invalid_int_raises(self, monkeypatch):
+        monkeypatch.setenv("FAKE_INT", "not_an_int")
+        with pytest.raises(ValueError):
+            FakeSettings.from_env()
+
+    def test_invalid_float_raises(self, monkeypatch):
+        monkeypatch.setenv("FAKE_FLOAT", "not_a_float")
+        with pytest.raises(ValueError):
+            FakeSettings.from_env()
+
+    def test_invalid_bool_raises(self, monkeypatch):
+        monkeypatch.setenv("FAKE_BOOL", "maybe")
+        with pytest.raises(ValueError, match="Invalid boolean"):
+            FakeSettings.from_env()
+
+
+# ---------------------------------------------------------------------------
+# Concrete env bindings tests
+# ---------------------------------------------------------------------------
+
+
+class TestMCPServerEnv:
+    def test_defaults(self, monkeypatch):
+        monkeypatch.delenv("AFK_CORS_ORIGINS", raising=False)
+        monkeypatch.delenv("AFK_MCP_NAME", raising=False)
+        monkeypatch.delenv("AFK_MCP_PORT", raising=False)
+
+        env = MCPServerEnv.from_env()
+        assert env.AFK_CORS_ORIGINS == []
+        assert env.AFK_MCP_NAME == "afk-mcp-server"
+        assert env.AFK_MCP_PORT == 8000
+        assert env.AFK_MCP_ENABLE_SSE is True
+        assert env.AFK_MCP_ENABLE_HEALTH is True
+        assert env.AFK_MCP_ALLOW_BATCH is True
+
+    def test_cors_origins_from_csv(self, monkeypatch):
+        monkeypatch.setenv("AFK_CORS_ORIGINS", "https://example.com, https://app.io")
+
+        env = MCPServerEnv.from_env()
+        assert env.AFK_CORS_ORIGINS == ["https://example.com", "https://app.io"]
+
+    def test_cors_origins_empty_string_is_empty_list(self, monkeypatch):
+        monkeypatch.setenv("AFK_CORS_ORIGINS", "")
+        env = MCPServerEnv.from_env()
+        assert env.AFK_CORS_ORIGINS == []
+
+    def test_bool_fields(self, monkeypatch):
+        monkeypatch.setenv("AFK_MCP_ENABLE_SSE", "false")
+        monkeypatch.setenv("AFK_MCP_ENABLE_HEALTH", "0")
+        monkeypatch.setenv("AFK_MCP_ALLOW_BATCH", "no")
+
+        env = MCPServerEnv.from_env()
+        assert env.AFK_MCP_ENABLE_SSE is False
+        assert env.AFK_MCP_ENABLE_HEALTH is False
+        assert env.AFK_MCP_ALLOW_BATCH is False
+
+
+class TestRunnerEnv:
+    def test_empty_allowlist_by_default(self, monkeypatch):
+        monkeypatch.delenv("AFK_ALLOWED_COMMANDS", raising=False)
+        env = RunnerEnv.from_env()
+        assert env.AFK_ALLOWED_COMMANDS == []
+
+    def test_allowlist_from_csv(self, monkeypatch):
+        monkeypatch.setenv("AFK_ALLOWED_COMMANDS", "ls, cat, rg, echo")
+        env = RunnerEnv.from_env()
+        assert env.AFK_ALLOWED_COMMANDS == ["ls", "cat", "rg", "echo"]
+
+
+class TestMemoryEnv:
+    def test_defaults(self, monkeypatch):
+        for var in (
+            "AFK_MEMORY_BACKEND",
+            "AFK_SQLITE_PATH",
+            "AFK_REDIS_HOST",
+            "AFK_REDIS_PORT",
+            "AFK_REDIS_DB",
+            "AFK_REDIS_PASSWORD",
+            "AFK_REDIS_EVENTS_MAX",
+            "AFK_PG_HOST",
+            "AFK_PG_PORT",
+            "AFK_PG_USER",
+            "AFK_PG_PASSWORD",
+            "AFK_PG_DB",
+            "AFK_PG_SSL",
+            "AFK_PG_POOL_MIN",
+            "AFK_PG_POOL_MAX",
+            "AFK_QUEUE_BACKEND",
+            "AFK_QUEUE_RETRY_BACKOFF_BASE_S",
+            "AFK_QUEUE_RETRY_BACKOFF_MAX_S",
+            "AFK_QUEUE_RETRY_BACKOFF_JITTER_S",
+            "AFK_QUEUE_REDIS_PREFIX",
+            "AFK_QUEUE_REDIS_HOST",
+            "AFK_QUEUE_REDIS_PORT",
+            "AFK_QUEUE_REDIS_DB",
+            "AFK_QUEUE_REDIS_PASSWORD",
+        ):
+            monkeypatch.delenv(var, raising=False)
+        monkeypatch.delenv("AFK_REDIS_URL", raising=False)
+        monkeypatch.delenv("AFK_PG_DSN", raising=False)
+        monkeypatch.delenv("AFK_VECTOR_DIM", raising=False)
+        monkeypatch.delenv("AFK_QUEUE_REDIS_URL", raising=False)
+
+        env = MemoryEnv.from_env()
+        assert env.AFK_MEMORY_BACKEND == "sqlite"
+        assert env.AFK_SQLITE_PATH == "afk_memory.sqlite3"
+        assert env.AFK_REDIS_HOST == "localhost"
+        assert env.AFK_REDIS_PORT == 6379
+        assert env.AFK_REDIS_DB == 0
+        assert env.AFK_REDIS_PASSWORD == ""
+        assert env.AFK_REDIS_EVENTS_MAX == 2000
+        assert env.AFK_PG_SSL is False
+        assert env.AFK_PG_POOL_MIN == 1
+        assert env.AFK_PG_POOL_MAX == 10
+        assert env.AFK_QUEUE_BACKEND == "inmemory"
+        assert env.AFK_QUEUE_RETRY_BACKOFF_BASE_S == 0.5
+        assert env.AFK_QUEUE_RETRY_BACKOFF_MAX_S == 30.0
+        assert env.AFK_QUEUE_RETRY_BACKOFF_JITTER_S == 0.2
+        assert env.AFK_QUEUE_REDIS_PREFIX == "afk:queue"
+        assert env.AFK_QUEUE_REDIS_HOST == "localhost"
+        assert env.AFK_QUEUE_REDIS_PORT == 6379
+        assert env.AFK_QUEUE_REDIS_DB == 0
+        assert env.AFK_QUEUE_REDIS_PASSWORD == ""
+
+    def test_redis_port_int(self, monkeypatch):
+        monkeypatch.setenv("AFK_REDIS_PORT", "9999")
+        env = MemoryEnv.from_env()
+        assert env.AFK_REDIS_PORT == 9999
+
+    def test_pg_ssl_bool(self, monkeypatch):
+        monkeypatch.setenv("AFK_PG_SSL", "true")
+        env = MemoryEnv.from_env()
+        assert env.AFK_PG_SSL is True
+
+    def test_backoff_floats(self, monkeypatch):
+        monkeypatch.setenv("AFK_QUEUE_RETRY_BACKOFF_BASE_S", "1.0")
+        monkeypatch.setenv("AFK_QUEUE_RETRY_BACKOFF_MAX_S", "60.0")
+        monkeypatch.setenv("AFK_QUEUE_RETRY_BACKOFF_JITTER_S", "0.5")
+        env = MemoryEnv.from_env()
+        assert env.AFK_QUEUE_RETRY_BACKOFF_BASE_S == 1.0
+        assert env.AFK_QUEUE_RETRY_BACKOFF_MAX_S == 60.0
+        assert env.AFK_QUEUE_RETRY_BACKOFF_JITTER_S == 0.5