feat(skills+terminal): make bundled skill scripts runnable out of the box (#13384)

* feat(skills): inject absolute skill dir and expand ${HERMES_SKILL_DIR} templates

When a skill loads, the activation message now exposes the absolute
skill directory and substitutes ${HERMES_SKILL_DIR} /
${HERMES_SESSION_ID} tokens in the SKILL.md body, so skills with
bundled scripts can instruct the agent to run them by absolute path
without an extra skill_view round-trip.

Also adds opt-in inline-shell expansion: !`cmd` snippets in SKILL.md
are pre-executed (with the skill directory as CWD) and their stdout is
inlined into the message before the agent reads it. Off by default —
enable via skills.inline_shell in config.yaml — because any snippet
runs on the host without approval.

Changes:
- agent/skill_commands.py: template substitution, inline-shell
  expansion, absolute skill-dir header, supporting-files list now
  shows both relative and absolute forms.
- hermes_cli/config.py: new skills.template_vars,
  skills.inline_shell, skills.inline_shell_timeout knobs.
- tests/agent/test_skill_commands.py: coverage for header, both
  template tokens (present and missing session id), template_vars
  disable, inline-shell default-off, enabled, CWD, and timeout.
- website/docs/developer-guide/creating-skills.md: documents the
  template tokens, the absolute-path header, and the opt-in inline
  shell with its security caveat.

Validation: tests/agent/ 1591 passed (includes 9 new tests).
E2E: loaded a real skill in an isolated HERMES_HOME; confirmed
${HERMES_SKILL_DIR} resolves to the absolute path, ${HERMES_SESSION_ID}
resolves to the passed task_id, !`date` runs when opt-in is set, and
stays literal when it isn't.

* feat(terminal): source ~/.bashrc (and user-listed init files) into session snapshot

bash login shells don't source ~/.bashrc, so tools that install themselves
there — nvm, asdf, pyenv, cargo, custom PATH exports — stay invisible to
the environment snapshot Hermes builds once per session.  Under systemd
or any context with a minimal parent env, that surfaces as
'node: command not found' in the terminal tool even though the binary
is reachable from every interactive shell on the machine.

Changes:
- tools/environments/local.py: before the login-shell snapshot bootstrap
  runs, prepend guarded 'source <file>' lines for each resolved init
  file.  Missing files are skipped, each source is wrapped with a
  '[ -r ... ] && . ... || true' guard so a broken rc can't abort the
  bootstrap.
- hermes_cli/config.py: new terminal.shell_init_files (explicit list,
  supports ~ and ${VAR}) and terminal.auto_source_bashrc (default on)
  knobs.  When shell_init_files is set it takes precedence; when it's
  empty and auto_source_bashrc is on, ~/.bashrc gets auto-sourced.
- tests/tools/test_local_shell_init.py: 10 tests covering the resolver
  (auto-bashrc, missing file, explicit override, ~/${VAR} expansion,
  opt-out) and the prelude builder (quoting, guarded sourcing), plus
  a real-LocalEnvironment snapshot test that confirms exports in the
  init file land in subsequent commands' environment.
- website/docs/reference/faq.md: documents the fix in Troubleshooting,
  including the zsh-user pattern of sourcing ~/.zshrc or nvm.sh
  directly via shell_init_files.

Validation: 10/10 new tests pass; tests/tools/test_local_*.py 40/40
pass; tests/agent/ 1591/1591 pass; tests/hermes_cli/test_config.py
50/50 pass.  E2E in an isolated HERMES_HOME: confirmed that a fake
~/.bashrc setting a marker var and PATH addition shows up in a real
LocalEnvironment().execute() call, that auto_source_bashrc=false
suppresses it, that an explicit shell_init_files entry wins over the
auto default, and that a missing bashrc is silently skipped.

tests/agent/test_skill_commands.py

@@ -405,3 +405,191 @@ class TestPlanSkillHelpers:
         assert "Add a /plan command" in msg
         assert ".hermes/plans/plan.md" in msg
         assert "Runtime note:" in msg
+
+
+class TestSkillDirectoryHeader:
+    """The activation message must expose the absolute skill directory and
+    explain how to resolve relative paths, so skills with bundled scripts
+    don't force the agent into a second ``skill_view()`` round-trip."""
+
+    def test_header_contains_absolute_skill_dir(self, tmp_path):
+        with patch("tools.skills_tool.SKILLS_DIR", tmp_path):
+            skill_dir = _make_skill(tmp_path, "abs-dir-skill")
+            scan_skill_commands()
+            msg = build_skill_invocation_message("/abs-dir-skill", "go")
+
+        assert msg is not None
+        assert f"[Skill directory: {skill_dir}]" in msg
+        assert "Resolve any relative paths" in msg
+
+    def test_supporting_files_shown_with_absolute_paths(self, tmp_path):
+        with patch("tools.skills_tool.SKILLS_DIR", tmp_path):
+            skill_dir = _make_skill(tmp_path, "scripted-skill")
+            (skill_dir / "scripts").mkdir()
+            (skill_dir / "scripts" / "run.js").write_text("console.log('hi')")
+            scan_skill_commands()
+            msg = build_skill_invocation_message("/scripted-skill")
+
+        assert msg is not None
+        # The supporting-files block must emit both the relative form (so the
+        # agent can call skill_view on it) and the absolute form (so it can
+        # run the script directly via terminal).
+        assert "scripts/run.js" in msg
+        assert str(skill_dir / "scripts" / "run.js") in msg
+        assert f"node {skill_dir}/scripts/foo.js" in msg
+
+
+class TestTemplateVarSubstitution:
+    """``${HERMES_SKILL_DIR}`` and ``${HERMES_SESSION_ID}`` in SKILL.md body
+    are replaced before the agent sees the content."""
+
+    def test_substitutes_skill_dir(self, tmp_path):
+        with patch("tools.skills_tool.SKILLS_DIR", tmp_path):
+            skill_dir = _make_skill(
+                tmp_path,
+                "templated",
+                body="Run: node ${HERMES_SKILL_DIR}/scripts/foo.js",
+            )
+            scan_skill_commands()
+            msg = build_skill_invocation_message("/templated")
+
+        assert msg is not None
+        assert f"node {skill_dir}/scripts/foo.js" in msg
+        # The literal template token must not leak through.
+        assert "${HERMES_SKILL_DIR}" not in msg.split("[Skill directory:")[0]
+
+    def test_substitutes_session_id_when_available(self, tmp_path):
+        with patch("tools.skills_tool.SKILLS_DIR", tmp_path):
+            _make_skill(
+                tmp_path,
+                "sess-templated",
+                body="Session: ${HERMES_SESSION_ID}",
+            )
+            scan_skill_commands()
+            msg = build_skill_invocation_message(
+                "/sess-templated", task_id="abc-123"
+            )
+
+        assert msg is not None
+        assert "Session: abc-123" in msg
+
+    def test_leaves_session_id_token_when_missing(self, tmp_path):
+        with patch("tools.skills_tool.SKILLS_DIR", tmp_path):
+            _make_skill(
+                tmp_path,
+                "sess-missing",
+                body="Session: ${HERMES_SESSION_ID}",
+            )
+            scan_skill_commands()
+            msg = build_skill_invocation_message("/sess-missing", task_id=None)
+
+        assert msg is not None
+        # No session — token left intact so the author can spot it.
+        assert "Session: ${HERMES_SESSION_ID}" in msg
+
+    def test_disable_template_vars_via_config(self, tmp_path):
+        with (
+            patch("tools.skills_tool.SKILLS_DIR", tmp_path),
+            patch(
+                "agent.skill_commands._load_skills_config",
+                return_value={"template_vars": False},
+            ),
+        ):
+            _make_skill(
+                tmp_path,
+                "no-sub",
+                body="Run: node ${HERMES_SKILL_DIR}/scripts/foo.js",
+            )
+            scan_skill_commands()
+            msg = build_skill_invocation_message("/no-sub")
+
+        assert msg is not None
+        # Template token must survive when substitution is disabled.
+        assert "${HERMES_SKILL_DIR}/scripts/foo.js" in msg
+
+
+class TestInlineShellExpansion:
+    """Inline ``!`cmd`` snippets in SKILL.md run before the agent sees the
+    content — but only when the user has opted in via config."""
+
+    def test_inline_shell_is_off_by_default(self, tmp_path):
+        with patch("tools.skills_tool.SKILLS_DIR", tmp_path):
+            _make_skill(
+                tmp_path,
+                "dyn-default-off",
+                body="Today is !`echo INLINE_RAN`.",
+            )
+            scan_skill_commands()
+            msg = build_skill_invocation_message("/dyn-default-off")
+
+        assert msg is not None
+        # Default config has inline_shell=False — snippet must stay literal.
+        assert "!`echo INLINE_RAN`" in msg
+        assert "Today is INLINE_RAN." not in msg
+
+    def test_inline_shell_runs_when_enabled(self, tmp_path):
+        with (
+            patch("tools.skills_tool.SKILLS_DIR", tmp_path),
+            patch(
+                "agent.skill_commands._load_skills_config",
+                return_value={"template_vars": True, "inline_shell": True,
+                              "inline_shell_timeout": 5},
+            ),
+        ):
+            _make_skill(
+                tmp_path,
+                "dyn-on",
+                body="Marker: !`echo INLINE_RAN`.",
+            )
+            scan_skill_commands()
+            msg = build_skill_invocation_message("/dyn-on")
+
+        assert msg is not None
+        assert "Marker: INLINE_RAN." in msg
+        assert "!`echo INLINE_RAN`" not in msg
+
+    def test_inline_shell_runs_in_skill_directory(self, tmp_path):
+        """Inline snippets get the skill dir as CWD so relative paths work."""
+        with (
+            patch("tools.skills_tool.SKILLS_DIR", tmp_path),
+            patch(
+                "agent.skill_commands._load_skills_config",
+                return_value={"template_vars": True, "inline_shell": True,
+                              "inline_shell_timeout": 5},
+            ),
+        ):
+            skill_dir = _make_skill(
+                tmp_path,
+                "dyn-cwd",
+                body="Here: !`pwd`",
+            )
+            scan_skill_commands()
+            msg = build_skill_invocation_message("/dyn-cwd")
+
+        assert msg is not None
+        assert f"Here: {skill_dir}" in msg
+
+    def test_inline_shell_timeout_does_not_break_message(self, tmp_path):
+        with (
+            patch("tools.skills_tool.SKILLS_DIR", tmp_path),
+            patch(
+                "agent.skill_commands._load_skills_config",
+                return_value={"template_vars": True, "inline_shell": True,
+                              "inline_shell_timeout": 1},
+            ),
+        ):
+            _make_skill(
+                tmp_path,
+                "dyn-slow",
+                body="Slow: !`sleep 5 && printf DYN_MARKER`",
+            )
+            scan_skill_commands()
+            msg = build_skill_invocation_message("/dyn-slow")
+
+        assert msg is not None
+        # Timeout is surfaced as a marker instead of propagating as an error,
+        # and the rest of the skill message still renders.
+        assert "inline-shell timeout" in msg
+        # The command's intended stdout never made it through — only the
+        # timeout marker (which echoes the command text) survives.
+        assert "DYN_MARKER" not in msg.replace("sleep 5 && printf DYN_MARKER", "")