diff --git a/openhands-agent-server/openhands/agent_server/docker/build.py b/openhands-agent-server/openhands/agent_server/docker/build.py
index 2389690ab5..4df53fed97 100755
--- a/openhands-agent-server/openhands/agent_server/docker/build.py
+++ b/openhands-agent-server/openhands/agent_server/docker/build.py
@@ -226,7 +226,10 @@ def _base_slug(image: str, max_len: int = 64) -> str:
 
     # Parse components from the slug form
     if "_tag_" in base_slug:
-        left, tag = base_slug.split("_tag_", 1)
+        # Ports also become "_tag_" (e.g., "ghcr.io:443/repo:tag"
+        # -> "ghcr.io_tag_443_s_repo_tag_tag"). Use rsplit so we split on the real
+        # image tag (the last _tag_), not the port.
+        left, tag = base_slug.rsplit("_tag_", 1)
     else:
         left, tag = base_slug, ""
 
@@ -234,7 +237,8 @@ def _base_slug(image: str, max_len: int = 64) -> str:
     repo = parts[-1] if parts else left  # last path segment is the repo
 
     # Reconstruct a compact, identifiable core: "<repo>[_tag_<tag>]"
-    ident = repo + (f"_tag_{tag}" if tag else "")
+    tag_piece = f"_tag_{tag}" if tag else ""
+    ident = repo + tag_piece
 
     # Fit within budget, reserving space for the digest suffix
     visible_budget = max_len - len(suffix)
@@ -242,8 +246,22 @@ def _base_slug(image: str, max_len: int = 64) -> str:
         f"max_len too small to fit digest suffix with length {len(suffix)}"
     )
 
-    kept = ident[:visible_budget]
-    return kept + suffix
+    if len(ident) > visible_budget:
+        if tag_piece and len(tag_piece) < visible_budget:
+            # Full tag fits: trim repo to make room
+            ident = repo[: visible_budget - len(tag_piece)] + tag_piece
+        else:
+            # Either no tag or tag too long: truncate from the start
+            ident = (tag_piece or ident)[:visible_budget]
+
+    truncated = ident + suffix
+    logger.debug(
+        "[base-slug] Truncated base image '%s' to slug '%s' (max_len=%d)",
+        image,
+        truncated,
+        max_len,
+    )
+    return truncated
 
 
 def _git_info() -> tuple[str, str]:
diff --git a/tests/agent_server/test_docker_build.py b/tests/agent_server/test_docker_build.py
index 2415493b64..b48ead839f 100644
--- a/tests/agent_server/test_docker_build.py
+++ b/tests/agent_server/test_docker_build.py
@@ -212,6 +212,39 @@ def test_base_slug_truncation_no_tag():
     assert "very-long-repository-name" in result
 
 
+def test_base_slug_preserves_latest_tag_suffix():
+    """Ensure tag_latest suffix is not mangled when truncating long slugs."""
+    from openhands.agent_server.docker.build import _base_slug
+
+    image = (
+        "docker.io/swebench/sweb.eval.x86_64.astropy_1776_astropy-8872:"
+        "tag_latest-0a797356ebce"
+    )
+
+    result = _base_slug(image, max_len=64)
+
+    assert len(result) <= 64
+    assert "tag_latest" in result
+    # Keep cache keys stable with digest suffix
+    assert result[-13:-12] == "-"
+    assert all(c in "0123456789abcdef" for c in result[-12:])
+
+
+def test_base_slug_preserves_tag_with_registry_port():
+    """Handle registries with ports without losing the tag segment."""
+    from openhands.agent_server.docker.build import _base_slug
+
+    image = (
+        "localhost:5001/swebench/sweb.eval.x86_64.astropy_1776_astropy-8872:"
+        "tag_latest-0a797356ebce"
+    )
+
+    result = _base_slug(image, max_len=64)
+
+    assert len(result) <= 64
+    assert "tag_latest" in result
+
+
 def test_base_slug_custom_max_len():
     """Test base_slug with custom max_len parameter."""
     from openhands.agent_server.docker.build import _base_slug