diff --git a/hermes_cli/version_info.py b/hermes_cli/version_info.py
index d3b4005adc..6fb7d32200 100644
--- a/hermes_cli/version_info.py
+++ b/hermes_cli/version_info.py
@@ -13,6 +13,7 @@ from __future__ import annotations
 
 import json
 import subprocess
+import tomllib
 from dataclasses import dataclass
 from pathlib import Path
 from typing import Literal, cast
@@ -82,6 +83,29 @@ def _parse_nonnegative(value: str | None) -> int | None:
     return parsed if parsed >= 0 else None
 
 
+def _calver_release_version(repo_dir: Path) -> tuple[str, int] | None:
+    """The version the nearest CalVer release shipped, and the commits since it.
+
+    Releases before semver tags existed are tagged ``vYYYY.M.D`` only; the
+    version users actually run is in that tag's pyproject. Without this, a
+    checkout past such a release would compare as "unknown" against plugins'
+    ``requires_hermes``.
+    """
+    described = _run_git(repo_dir, "describe", "--tags", "--long", "--match", "v2[0-9][0-9][0-9].*", "HEAD")
+    if not described:
+        return None
+    tag, count, _ = described.rsplit("-", 2)
+    distance = _parse_nonnegative(count)
+    try:
+        project = tomllib.loads(_run_git(repo_dir, "show", f"{tag}:pyproject.toml") or "").get("project", {})
+    except tomllib.TOMLDecodeError:
+        return None
+    version = project.get("version")
+    if distance is None or not isinstance(version, str) or not STABLE_TAG_RE.fullmatch(f"v{version}"):
+        return None
+    return version, distance
+
+
 # --- Install stamp reader ---------------------------------------------------
 
 def _resolve_stamp_file() -> Path | None:
@@ -212,6 +236,8 @@ def _git_version_info(repo_dir: Path, *, include_untracked: bool = False) -> Ver
     distance = _parse_nonnegative(
         _run_git(repo_dir, "rev-list", "--count", f"v{base_version}..HEAD")
     ) if releases else None
+    if not releases:
+        base_version, distance = _calver_release_version(repo_dir) or ("unknown", None)
     short_commit = _run_git(repo_dir, "rev-parse", "--short=7", "HEAD")
     if base_version == "unknown" and short_commit:
         display_version = f"git.{short_commit}{'.dirty' if dirty else ''}"
diff --git a/tests/hermes_cli/test_version_info.py b/tests/hermes_cli/test_version_info.py
index 033f0d7edd..4f166f706a 100644
--- a/tests/hermes_cli/test_version_info.py
+++ b/tests/hermes_cli/test_version_info.py
@@ -150,6 +150,38 @@ def test_get_version_info_derives_identity_from_reachable_release_tag(tmp_path,
     assert info.source == "git"
 
 
+def test_get_version_info_takes_the_version_a_calver_only_release_shipped(tmp_path, monkeypatch):
+    """Releases tagged only vYYYY.M.D resolve to their pyproject version, not "unknown"."""
+    repo = tmp_path / "repo"
+    repo.mkdir()
+
+    def git(*args: str) -> str:
+        result = subprocess.run(
+            ["git", *args], cwd=repo, text=True, capture_output=True, check=True,
+            env={"HOME": str(tmp_path), "PATH": __import__("os").environ["PATH"]},
+        )
+        return result.stdout.strip()
+
+    git("init", "-q")
+    git("config", "user.name", "Hermes Test")
+    git("config", "user.email", "hermes@example.invalid")
+    (repo / "pyproject.toml").write_text('[project]\nname = "hermes-agent"\nversion = "0.21.4"\n', encoding="utf-8")
+    git("add", "pyproject.toml")
+    git("commit", "-qm", "release")
+    git("tag", "v2026.9.21")
+    (repo / "pyproject.toml").write_text('[project]\nname = "hermes-agent"\nversion = "0.0.0"\n', encoding="utf-8")
+    git("commit", "-qam", "next")
+
+    monkeypatch.setattr("hermes_cli.version_info._resolve_stamp_file", lambda: None)
+    monkeypatch.setattr("hermes_cli.version_info._resolve_repo_dir", lambda: repo)
+
+    info = get_version_info()
+
+    assert info.base_version == "0.21.4"
+    assert info.distance == 1
+    assert info.derived_version == f"0.21.4+1.g{git('rev-parse', '--short=7', 'HEAD')}"
+
+
 def test_resolve_stamp_file_honors_install_root(tmp_path, monkeypatch):
     """Sealed installs (the Nix wrapper) point HERMES_INSTALL_ROOT at the stamp dir."""
     stamp = {"commit": "e" * 40, "source": "nix", "distribution": "nix", "updateMechanism": "external"}