feat: multi-agent architecture — named agents with routing, tool policies, and isolated workspaces

Implements the full multi-agent system for Hermes Agent, allowing a single
installation to host multiple named agents, each with its own model,
personality, toolset, workspace, and session history.

## New Files

- gateway/agent_registry.py: AgentConfig, ToolPolicy, SubagentPolicy,
  AgentRegistry, TOOL_PROFILES (minimal/coding/messaging/full), and
  normalize_tool_config() for shorthand YAML parsing

- gateway/router.py: BindingRouter with 7-tier deterministic routing
  (chat_id > peer > guild+type > guild > platform+type > platform > default)

## Core Changes

- model_tools.py: get_tool_definitions() accepts agent_tool_policy for
  per-agent tool filtering; handle_function_call() extended enabled_tools
  check to gate ALL tool calls (defense-in-depth)

- gateway/session.py: build_session_key() now accepts agent_id and dm_scope
  parameters, replacing hardcoded 'agent:main' with 'agent:{agent_id}'

- tools/memory_tool.py: MemoryStore accepts memory_dir parameter for
  per-agent memory isolation

- agent/prompt_builder.py: build_context_files_prompt() accepts
  agent_workspace for SOUL.md lookup; build_skills_system_prompt()
  accepts agent_skills_dir for per-agent skill overlay

- run_agent.py: AIAgent accepts agent_tool_policy and agent_workspace,
  passes policy through to get_tool_definitions()

- gateway/run.py: Initializes AgentRegistry + BindingRouter, resolves
  agent per-message in _handle_message(), passes config to _run_agent(),
  adds /agents command

- cli.py: --agent flag for selecting named agent profiles, /agents
  slash command, agent config override for model/personality/tools

- hermes_cli/config.py: agents/bindings in DEFAULT_CONFIG, version 7

- tools/delegate_tool.py: Configurable max_depth per-agent, tool policy
  inheritance from parent to child

## Config Format

agents:
  main:
    default: true
  coder:
    model: anthropic/claude-sonnet-4
    personality: 'You are a coding assistant.'
    tools: coding  # or [tool1, tool2] or {profile: x, deny: [...]}

bindings:
  - agent: coder
    telegram: '-100123456'

## Tests

168 new tests across 3 test files (agent_registry, router, integration).
All 3106 tests pass.

agent/prompt_builder.py

@@ -179,10 +179,12 @@ def _skill_is_platform_compatible(skill_file: Path) -> bool:
         return True  # Err on the side of showing the skill
 
 
-def build_skills_system_prompt() -> str:
+def build_skills_system_prompt(agent_skills_dir: Optional[Path] = None) -> str:
     """Build a compact skill index for the system prompt.
 
     Scans ~/.hermes/skills/ for SKILL.md files grouped by category.
+    When agent_skills_dir is provided and exists, also scans it for SKILL.md
+    files. Agent skills take priority (listed first in each category).
     Includes per-skill descriptions from frontmatter so the model can
     match skills by meaning, not just name.
     Filters out skills incompatible with the current OS platform.
@@ -190,33 +192,36 @@ def build_skills_system_prompt() -> str:
     hermes_home = Path(os.getenv("HERMES_HOME", Path.home() / ".hermes"))
     skills_dir = hermes_home / "skills"
 
-    if not skills_dir.exists():
-        return ""
-
     # Collect skills with descriptions, grouped by category
     # Each entry: (skill_name, description)
     # Supports sub-categories: skills/mlops/training/axolotl/SKILL.md
     # → category "mlops/training", skill "axolotl"
     skills_by_category: dict[str, list[tuple[str, str]]] = {}
-    for skill_file in skills_dir.rglob("SKILL.md"):
-        # Skip skills incompatible with the current OS platform
-        if not _skill_is_platform_compatible(skill_file):
-            continue
-        rel_path = skill_file.relative_to(skills_dir)
-        parts = rel_path.parts
-        if len(parts) >= 2:
-            # Category is everything between skills_dir and the skill folder
-            # e.g. parts = ("mlops", "training", "axolotl", "SKILL.md")
-            #   → category = "mlops/training", skill_name = "axolotl"
-            # e.g. parts = ("github", "github-auth", "SKILL.md")
-            #   → category = "github", skill_name = "github-auth"
-            skill_name = parts[-2]
-            category = "/".join(parts[:-2]) if len(parts) > 2 else parts[0]
-        else:
-            category = "general"
-            skill_name = skill_file.parent.name
-        desc = _read_skill_description(skill_file)
-        skills_by_category.setdefault(category, []).append((skill_name, desc))
+
+    def _scan_skills_dir(scan_dir: Path):
+        """Scan a directory for SKILL.md files and add them to skills_by_category."""
+        if not scan_dir.exists():
+            return
+        for skill_file in scan_dir.rglob("SKILL.md"):
+            if not _skill_is_platform_compatible(skill_file):
+                continue
+            rel_path = skill_file.relative_to(scan_dir)
+            parts = rel_path.parts
+            if len(parts) >= 2:
+                skill_name = parts[-2]
+                category = "/".join(parts[:-2]) if len(parts) > 2 else parts[0]
+            else:
+                category = "general"
+                skill_name = skill_file.parent.name
+            desc = _read_skill_description(skill_file)
+            skills_by_category.setdefault(category, []).append((skill_name, desc))
+
+    # Agent skills first (so they appear first / take priority)
+    if agent_skills_dir is not None:
+        _scan_skills_dir(agent_skills_dir)
+
+    # Then global skills
+    _scan_skills_dir(skills_dir)
 
     if not skills_by_category:
         return ""
@@ -284,11 +289,11 @@ def _truncate_content(content: str, filename: str, max_chars: int = CONTEXT_FILE
     return head + marker + tail
 
 
-def build_context_files_prompt(cwd: Optional[str] = None) -> str:
+def build_context_files_prompt(cwd: Optional[str] = None, agent_workspace: Optional[Path] = None) -> str:
     """Discover and load context files for the system prompt.
 
     Discovery: AGENTS.md (recursive), .cursorrules / .cursor/rules/*.mdc,
-    SOUL.md (cwd then ~/.hermes/ fallback). Each capped at 20,000 chars.
+    SOUL.md (agent_workspace then cwd then ~/.hermes/ fallback). Each capped at 20,000 chars.
     """
     if cwd is None:
         cwd = os.getcwd()
@@ -356,13 +361,20 @@ def build_context_files_prompt(cwd: Optional[str] = None) -> str:
         cursorrules_content = _truncate_content(cursorrules_content, ".cursorrules")
         sections.append(cursorrules_content)
 
-    # SOUL.md (cwd first, then ~/.hermes/ fallback)
+    # SOUL.md (agent_workspace first, then cwd, then ~/.hermes/ fallback)
     soul_path = None
-    for name in ["SOUL.md", "soul.md"]:
-        candidate = cwd_path / name
-        if candidate.exists():
-            soul_path = candidate
-            break
+    if agent_workspace is not None:
+        for name in ["SOUL.md", "soul.md"]:
+            candidate = agent_workspace / name
+            if candidate.exists():
+                soul_path = candidate
+                break
+    if not soul_path:
+        for name in ["SOUL.md", "soul.md"]:
+            candidate = cwd_path / name
+            if candidate.exists():
+                soul_path = candidate
+                break
     if not soul_path:
         global_soul = Path.home() / ".hermes" / "SOUL.md"
         if global_soul.exists():