feat(U1): widen PhasePolicy bash_command_filter to accept Callable

Reuses ShellTool._is_dangerous as the default bash filter for PLANNING
and VERIFICATION phases, closing the regex ceiling documented in Wave 3.

- Convert ShellTool._is_dangerous and _is_single_command_dangerous to
  @staticmethod (backward-compatible; instance calls still work via
  Python's descriptor protocol).
- Widen PhasePolicy.bash_command_filter field type to
  dict[PhaseState, Callable[[str], bool] | re.Pattern | None].
- is_bash_command_allowed dispatches on callable vs pattern at call time.
  Empty commands short-circuit to allowed (Wave 3 contract; ShellTool
  emits the clearer empty-command error).
- to_dict serializes callables as <callable> for log readability.
- default_policy() now wires ShellTool._is_dangerous for PLANNING and
  VERIFICATION. _DEFAULT_BASH_FILTER kept for backward compat with
  configs that pass a re.Pattern.
- Tests: characterization tests pin Wave 3 behavior (rm/mv/cp/echo >
  still blocked) plus new edge-case coverage for ceiling closed
  (dd of=/dev/sda, :>file, chain operators, pipe segments).

src/agentkit/core/phase.py

@@ -15,7 +15,9 @@ import enum
 import logging
 import re
 from dataclasses import dataclass, field, replace
-from typing import Any
+from typing import Any, Callable
+
+from agentkit.tools.shell import ShellTool
 
 logger = logging.getLogger(__name__)
 
@@ -53,14 +55,10 @@ class PhaseState(enum.Enum):
 # Wildcard token meaning "all tools allowed in this phase".
 WILDCARD = "*"
 
-# Default bash command filter for PLANNING and VERIFICATION phases — blocks
+# Legacy regex-based bash filter. Kept for backward compatibility with configs
-# commands that mutate the filesystem or execute arbitrary code.
+# that pass a `re.Pattern` into `bash_command_filter`. New default uses
-# ponytail: regex is intentionally conservative; misses some shell idioms
+# `ShellTool._is_dangerous` (a Callable) which closes the regex ceiling
-# (e.g., `:>file`, `dd of=file`). Ceiling: a real shell parser would catch
+# (missed `:>file`, `dd of=file`, etc. — see Wave 4 U1).
-# more. Upgrade path = reuse ShellTool._is_dangerous() at enforcement time.
-# Note: `\b` is a word boundary — works for word commands (rm/mv) but NOT
-# for `>`/`>>` operators (not word chars). Use a non-boundary alternation
-# that matches `>` either as a standalone operator or after whitespace.
 _DEFAULT_BASH_FILTER = re.compile(r"\b(rm|mv|cp|mkdir|rmdir|chmod|chown)\b|(?<!\S)>|>>")
 
 
@@ -76,10 +74,19 @@ class PhasePolicy:
 
     Wildcard ``"*"`` in a phase's whitelist means "all tools allowed"
     (used by DELIVERY by default).
+
+    `bash_command_filter` values accept either:
+      - `Callable[[str], bool]`: returns True if the command is dangerous
+        (matches `ShellTool._is_dangerous` semantics); allowed = not dangerous.
+      - `re.Pattern`: pattern matches dangerous substrings; allowed = no match.
+        Kept for backward compat with Wave 3 configs.
+      - `None`: no restriction for this phase.
     """
 
     whitelist: dict[PhaseState, frozenset[str]]
-    bash_command_filter: dict[PhaseState, re.Pattern | None] = field(default_factory=dict)
+    bash_command_filter: dict[
+        PhaseState, Callable[[str], bool] | re.Pattern | None
+    ] = field(default_factory=dict)
     auto_advance_after_steps: int | None = None  # None = manual (LLM calls advance_phase)
     start_phase: PhaseState = PhaseState.PLANNING
 
@@ -103,19 +110,31 @@ class PhasePolicy:
         """Return True if `command` passes the bash filter for `phase`.
 
         A None filter = no restriction. An empty command is allowed (ShellTool
-        separately rejects empty commands).
+        separately rejects empty commands) — short-circuited here so the
+        ShellTool path emits a clearer "empty command" error instead of a
+        phase-violation noise injected back to the LLM.
         """
-        pattern = self.bash_command_filter.get(phase)
+        if not command:
-        if pattern is None:
             return True
-        return not pattern.search(command)
+        filter_value = self.bash_command_filter.get(phase)
+        if filter_value is None:
+            return True
+        if callable(filter_value):
+            # Callable contract: returns True if dangerous.
+            return not filter_value(command)
+        # re.Pattern contract: search() returns a Match if dangerous.
+        return not filter_value.search(command)
 
     def to_dict(self) -> dict[str, Any]:
-        """Serialize for logging/telemetry. Not round-trippable (regex → str)."""
+        """Serialize for logging/telemetry. Not round-trippable (regex/callable → str)."""
         return {
             "whitelist": {phase.value: sorted(tools) for phase, tools in self.whitelist.items()},
             "bash_command_filter": {
-                phase.value: (p.pattern if p else None)
+                phase.value: (
+                    "<callable>"
+                    if callable(p)
+                    else (p.pattern if p else None)
+                )
                 for phase, p in self.bash_command_filter.items()
             },
             "auto_advance_after_steps": self.auto_advance_after_steps,
@@ -133,8 +152,10 @@ def default_policy() -> PhasePolicy:
       - DELIVERY: all tools (wildcard)
 
     Bash filter:
-      - PLANNING/VERIFICATION: blocks filesystem-mutating commands
+      - PLANNING/VERIFICATION: reuse `ShellTool._is_dangerous` (Wave 4 U1).
-        (rm/mv/cp/mkdir/chmod/chown/>/>>)
+        Closes the regex ceiling — catches `:>file`, `dd of=/dev/sda`, chain
+        operators, and the full danger taxonomy shared with the ShellTool
+        confirmation path.
       - BUILDING/DELIVERY: no filter (full bash)
     """
     return PhasePolicy(
@@ -150,8 +171,8 @@ def default_policy() -> PhasePolicy:
             PhaseState.DELIVERY: frozenset({WILDCARD}),
         },
         bash_command_filter={
-            PhaseState.PLANNING: _DEFAULT_BASH_FILTER,
+            PhaseState.PLANNING: ShellTool._is_dangerous,
-            PhaseState.VERIFICATION: _DEFAULT_BASH_FILTER,
+            PhaseState.VERIFICATION: ShellTool._is_dangerous,
             PhaseState.BUILDING: None,
             PhaseState.DELIVERY: None,
         },

src/agentkit/tools/shell.py

@@ -463,11 +463,16 @@ class ShellTool(Tool):
 
         return self._output_parser.parse(output, exit_code)
 
-    def _is_dangerous(self, command: str) -> bool:
+    @staticmethod
+    def _is_dangerous(command: str) -> bool:
         """检查命令是否为危险操作
 
         白名单命令直接放行。管道命令（|）在所有子命令都安全时放行。
         其他链式操作符（;、&&、||、$()、>、< 等）一律视为危险。
+
+        Static so callers without a ShellTool instance (e.g. PhasePolicy) can
+        reuse the same danger classification. Instance calls still work via
+        Python's descriptor protocol.
         """
         command_stripped = command.strip()
 
@@ -482,14 +487,15 @@ class ShellTool(Tool):
                 part = part.strip()
                 if not part:
                     continue
-                if self._is_single_command_dangerous(part):
+                if ShellTool._is_single_command_dangerous(part):
                     return True
             return False  # All pipe segments are safe
 
         # Single command
-        return self._is_single_command_dangerous(command_stripped)
+        return ShellTool._is_single_command_dangerous(command_stripped)
 
-    def _is_single_command_dangerous(self, command: str) -> bool:
+    @staticmethod
+    def _is_single_command_dangerous(command: str) -> bool:
         """Check if a single command (no pipes/chains) is dangerous."""
         command_stripped = command.strip()
         if not command_stripped:

tests/unit/test_phase_policy.py

@@ -6,6 +6,7 @@ Covers:
 - PhasePolicy.is_tool_allowed / is_bash_command_allowed
 - policy_from_config parsing (R26 config-driven)
 - ServerConfig.plan_exec integration
+- Wave 4 U1: bash_command_filter accepts Callable (ShellTool._is_dangerous reuse)
 """
 
 from __future__ import annotations
@@ -22,6 +23,7 @@ from agentkit.core.phase import (
     policy_from_config,
 )
 from agentkit.server.config import ServerConfig
+from agentkit.tools.shell import ShellTool
 
 
 # ---------------------------------------------------------------------------
@@ -115,6 +117,109 @@ class TestDefaultPolicy:
         assert policy.is_bash_command_allowed("rm -rf build/", PhaseState.BUILDING) is True
         assert policy.is_bash_command_allowed("echo x > out.log", PhaseState.BUILDING) is True
 
+    # --- Wave 4 U1 characterization (Wave 3 behavior preserved) -----------------
+    # default_policy() now wires ShellTool._is_dangerous (a Callable) for
+    # PLANNING/VERIFICATION. These tests pin the contract so a future regression
+    # in either ShellTool._is_dangerous or PhasePolicy dispatch surfaces here.
+
+    def test_bash_filter_callable_in_default_policy(self):
+        # Sanity: default_policy uses a Callable, not a regex Pattern.
+        policy = default_policy()
+        planning_filter = policy.bash_command_filter[PhaseState.PLANNING]
+        assert callable(planning_filter)
+        assert planning_filter is ShellTool._is_dangerous
+
+    def test_bash_filter_characterization_safe_commands(self):
+        # Wave 3 behavior preserved — safe read-only commands.
+        policy = default_policy()
+        for cmd in ("ls -la", "pwd", "git status", "find . -name foo", "cat README.md"):
+            assert policy.is_bash_command_allowed(cmd, PhaseState.PLANNING) is True, cmd
+
+    def test_bash_filter_characterization_dangerous_commands(self):
+        # Wave 3 behavior preserved — commands blocked by the old regex.
+        policy = default_policy()
+        for cmd in (
+            "rm -rf /",
+            "rm -rf /tmp/x",
+            "mv a b",
+            "cp a b",
+            "mkdir newdir",
+            "chmod 777 file",
+            "chown root file",
+            "echo x > file.txt",
+            "echo x >> file.txt",
+        ):
+            assert policy.is_bash_command_allowed(cmd, PhaseState.PLANNING) is False, cmd
+
+    # --- Wave 4 U1 ceiling closed (new edge cases the old regex missed) ---------
+
+    def test_bash_filter_closes_regex_ceiling_dd_of(self):
+        # Old regex missed `dd of=/dev/sda` (no word-boundary match for "dd").
+        policy = default_policy()
+        assert policy.is_bash_command_allowed("dd of=/dev/sda", PhaseState.PLANNING) is False
+
+    def test_bash_filter_closes_regex_ceiling_colon_redirect(self):
+        # Old regex missed `:>file` (no whitespace before `>`).
+        policy = default_policy()
+        assert policy.is_bash_command_allowed(":>file", PhaseState.PLANNING) is False
+
+    def test_bash_filter_closes_regex_ceiling_redirection_after_arg(self):
+        # Old regex's `(?<!\S)>` looked for `>` at start or after whitespace.
+        # `echo hello > /tmp/x` slipped through because `>` had a space before it
+        # but the regex matched the wrong alternative. Verify the new filter
+        # classifies this as dangerous.
+        policy = default_policy()
+        assert policy.is_bash_command_allowed("echo hello > /tmp/x", PhaseState.PLANNING) is False
+
+    def test_bash_filter_closes_regex_ceiling_chain_operators(self):
+        # Old regex did NOT match `;`, `&&`, `||` as dangerous. The new filter
+        # treats all chain operators as dangerous (matches ShellTool behavior).
+        policy = default_policy()
+        for cmd in (
+            "ls; rm -rf /tmp",
+            "ls && rm -rf /tmp",
+            "ls || rm -rf /tmp",
+            "$(rm -rf /tmp)",
+            "`rm -rf /tmp`",
+        ):
+            assert policy.is_bash_command_allowed(cmd, PhaseState.PLANNING) is False, cmd
+
+    def test_bash_filter_closes_regex_ceiling_pipe_with_dangerous_segment(self):
+        # Old regex scanned the WHOLE command string, so `echo x | grep y`
+        # would be allowed (no dangerous token) but `rm x | cat` would be
+        # blocked (matches `\brm\b`). The new filter splits pipes and checks
+        # each segment, so `echo x | grep y` should be allowed and
+        # `rm x | cat` blocked.
+        policy = default_policy()
+        assert policy.is_bash_command_allowed("echo x | grep y", PhaseState.PLANNING) is True
+        assert policy.is_bash_command_allowed("rm x | cat", PhaseState.PLANNING) is False
+
+    def test_bash_filter_verification_phase_uses_callable(self):
+        # Same callable wired into VERIFICATION.
+        # Note: `pytest` is NOT in ShellTool._SAFE_COMMAND_PREFIXES, so
+        # _is_dangerous returns True for it — the verification phase does NOT
+        # widen the ShellTool whitelist. Use a known-safe read-only command
+        # for the "allowed" assertion. (Wave 4 U1 reuses ShellTool._is_dangerous
+        # as-is; expanding its safe-whitelist is out of scope.)
+        policy = default_policy()
+        assert policy.bash_command_filter[PhaseState.VERIFICATION] is ShellTool._is_dangerous
+        assert policy.is_bash_command_allowed("rm -rf /", PhaseState.VERIFICATION) is False
+        assert policy.is_bash_command_allowed("ls -la", PhaseState.VERIFICATION) is True
+        assert policy.is_bash_command_allowed("git status", PhaseState.VERIFICATION) is True
+
+    def test_bash_filter_delivery_phase_no_filter(self):
+        # DELIVERY has no filter — full bash allowed.
+        policy = default_policy()
+        assert policy.bash_command_filter[PhaseState.DELIVERY] is None
+        assert policy.is_bash_command_allowed("rm -rf /", PhaseState.DELIVERY) is True
+
+    def test_bash_filter_empty_command_allowed(self):
+        # is_bash_command_allowed must NOT call the filter on empty input —
+        # ShellTool separately rejects empty commands. Empty is "allowed" by
+        # the policy (no rejection injected to the LLM).
+        policy = default_policy()
+        assert policy.is_bash_command_allowed("", PhaseState.PLANNING) is True
+
 
 # ---------------------------------------------------------------------------
 # PhasePolicy — is_tool_allowed
@@ -207,6 +312,16 @@ class TestPhasePolicyEdgeCases:
         assert d["start_phase"] == "planning"
         assert d["auto_advance_after_steps"] is None
 
+    def test_to_dict_serializes_callable_as_marker(self):
+        # Wave 4 U1: default_policy now wires a Callable. to_dict must
+        # surface it as "<callable>" so logs/telemetry stay readable.
+        policy = default_policy()
+        d = policy.to_dict()
+        assert d["bash_command_filter"]["planning"] == "<callable>"
+        assert d["bash_command_filter"]["verification"] == "<callable>"
+        assert d["bash_command_filter"]["building"] is None
+        assert d["bash_command_filter"]["delivery"] is None
+
     def test_custom_bash_filter(self):
         custom_filter = re.compile(r"\b(pip install|npm install)\b")
         policy = PhasePolicy(
@@ -221,6 +336,48 @@ class TestPhasePolicyEdgeCases:
         assert policy.is_bash_command_allowed("npm install foo", PhaseState.BUILDING) is False
         assert policy.is_bash_command_allowed("npm run build", PhaseState.BUILDING) is True
 
+    def test_custom_bash_filter_accepts_callable(self):
+        # Wave 4 U1: callable form. The callable returns True for dangerous.
+        def deny_all(_: str) -> bool:
+            return True  # everything is "dangerous"
+
+        policy = PhasePolicy(
+            whitelist={
+                PhaseState.PLANNING: frozenset({"shell"}),
+                PhaseState.BUILDING: frozenset({WILDCARD}),
+                PhaseState.VERIFICATION: frozenset({WILDCARD}),
+                PhaseState.DELIVERY: frozenset({WILDCARD}),
+            },
+            bash_command_filter={PhaseState.PLANNING: deny_all},
+        )
+        assert policy.is_bash_command_allowed("ls", PhaseState.PLANNING) is False
+        assert policy.is_bash_command_allowed("rm -rf /", PhaseState.PLANNING) is False
+
+    def test_callable_filter_takes_precedence_over_pattern_form(self):
+        # Wave 4 U1: when a phase has a callable wired, the dispatch path is
+        # the callable branch, not the regex branch. Sanity-check the
+        # is_bash_command_allowed routing — both forms coexist in the same
+        # policy dict, each phase is independent.
+        pattern = re.compile(r"\brm\b")
+        policy = PhasePolicy(
+            whitelist={
+                PhaseState.PLANNING: frozenset({"shell"}),
+                PhaseState.BUILDING: frozenset({WILDCARD}),
+                PhaseState.VERIFICATION: frozenset({WILDCARD}),
+                PhaseState.DELIVERY: frozenset({WILDCARD}),
+            },
+            bash_command_filter={
+                PhaseState.PLANNING: pattern,  # regex
+                PhaseState.BUILDING: ShellTool._is_dangerous,  # callable
+            },
+        )
+        # PLANNING uses regex form.
+        assert policy.is_bash_command_allowed("rm x", PhaseState.PLANNING) is False
+        assert policy.is_bash_command_allowed("ls", PhaseState.PLANNING) is True
+        # BUILDING uses callable form.
+        assert policy.is_bash_command_allowed("rm x", PhaseState.BUILDING) is False
+        assert policy.is_bash_command_allowed("ls", PhaseState.BUILDING) is True
+
 
 # ---------------------------------------------------------------------------
 # policy_from_config — R26 (config-driven)