feat(cli): warn on unsupported pip installs + fix stale update-check cache (#34491) (#34846)

* docs(code-execution): document HERMES_* env narrowing + passthrough workaround

The execute_code sandbox-child env scrub (108397726, #27303) deliberately
dropped the broad HERMES_ prefix passthrough, keeping only an operational
4-var allowlist (HERMES_HOME/PROFILE/CONFIG/ENV). A script that relied on a
non-secret HERMES_* var (HERMES_BASE_URL, HERMES_KANBAN_DB, HERMES_*_WEBHOOK,
or a plugin-defined one) now sees it unset in the child.

Document the behavior change and the two recovery routes (terminal.env_passthrough
in config.yaml, or required_environment_variables in skill frontmatter), plus
the debug log line that surfaces the drop for diagnosis.

* feat(cli): warn on unsupported pip installs + fix stale update-check cache after pip upgrade

Banner now shows a yellow warning when detect_install_method() == 'pip':
'pip install hermes-agent' isn't the supported install path (it exists on
PyPI for internal/CI reasons), so updates and issue support don't behave
correctly. Reuses existing install-method detection; warn, never block.

Also fixes #34491: check_for_updates() keyed its 6h cache only on ts+rev.
On the pip path (no HERMES_REVISION), rev is always None, so a
'pip install --upgrade' changed VERSION but left the cache valid — the
stale 'N commits behind' count survived the upgrade. Cache now also keys
on the installed VERSION and invalidates on mismatch.

hermes_cli/banner.py

@@ -221,7 +221,11 @@ def check_for_updates() -> Optional[int]:
     cache_file = hermes_home / ".update_check"
     embedded_rev = os.environ.get("HERMES_REVISION") or None
 
-    # Read cache — invalidate if the embedded rev has changed since last check
+    # Read cache — invalidate if the embedded rev OR installed version has
+    # changed since the last check. The version guard matters for pip installs:
+    # `check_via_pypi()` compares against VERSION, so a `pip install --upgrade`
+    # changes VERSION but leaves rev unchanged (both None), and without this
+    # the stale "behind" count would survive the upgrade for up to 6h. See #34491.
     now = time.time()
     try:
         if cache_file.exists():
@@ -229,6 +233,7 @@ def check_for_updates() -> Optional[int]:
             if (
                 now - cached.get("ts", 0) < _UPDATE_CHECK_CACHE_SECONDS
                 and cached.get("rev") == embedded_rev
+                and cached.get("ver") == VERSION
             ):
                 return cached.get("behind")
     except Exception:
@@ -249,7 +254,9 @@ def check_for_updates() -> Optional[int]:
             behind = _check_via_local_git(repo_dir)
 
     try:
-        cache_file.write_text(json.dumps({"ts": now, "behind": behind, "rev": embedded_rev}))
+        cache_file.write_text(
+            json.dumps({"ts": now, "behind": behind, "rev": embedded_rev, "ver": VERSION})
+        )
     except Exception:
         pass
 
@@ -691,6 +698,21 @@ def build_welcome_banner(console: Console, model: str, cwd: str,
     except Exception:
         pass  # Never break the banner over an update check
 
+    # Pip-install warning — `pip install hermes-agent` is not the supported
+    # install path (it exists on PyPI for internal/CI reasons, not end users).
+    # Such installs miss the git checkout + installer-managed deps, so updates,
+    # self-update, and issue triage don't behave correctly. Warn, don't block.
+    try:
+        from hermes_cli.config import detect_install_method
+        if detect_install_method() == "pip":
+            right_lines.append(
+                "[bold yellow]⚠ pip install not officially supported[/]"
+                "[dim yellow] — exists for reasons other than user install; "
+                "expect instability and an inability to support issues[/]"
+            )
+    except Exception:
+        pass  # Never break the banner over the install-method check
+
     right_content = "\n".join(right_lines)
     layout_table.add_row(left_content, right_content)