diff --git a/CHANGELOG.md b/CHANGELOG.md
index 173a46596..1307da034 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - `apm install` no longer silently drops skills, agents, and commands when a Claude Code plugin also ships `hooks/*.json`. The package-type detection cascade now classifies plugin-shaped packages as `MARKETPLACE_PLUGIN` (which already maps hooks via the plugin synthesizer) before falling back to the hook-only classification, and emits a default-visibility `[!]` warning when a hook-only classification disagrees with the package's directory contents (#780)
 - Preserve custom git ports across protocols: non-default ports on `ssh://` and `https://` dependency URLs (e.g. Bitbucket Datacenter on SSH port 7999, self-hosted GitLab on HTTPS port 8443) are now captured as a first-class `port` field on `DependencyReference` and threaded through all clone URL builders. When the SSH clone fails, the HTTPS fallback reuses the same port instead of silently dropping it (#661, #731)
+- Detect port-like first path segment in SCP shorthand (`git@host:7999/path`) and raise an actionable error suggesting the `ssh://` URL form, instead of silently misparsing the port as part of the repository path (#784)
 
 ## [0.8.12] - 2026-04-19
 
diff --git a/src/apm_cli/models/dependency/reference.py b/src/apm_cli/models/dependency/reference.py
index bcdb1ffdb..742c94522 100644
--- a/src/apm_cli/models/dependency/reference.py
+++ b/src/apm_cli/models/dependency/reference.py
@@ -665,11 +665,41 @@ def _parse_ssh_url(dependency_str: str):
         else:
             repo_part = ssh_repo_part
 
-        if repo_part.endswith(".git"):
+        had_git_suffix = repo_part.endswith(".git")
+        if had_git_suffix:
             repo_part = repo_part[:-4]
 
         repo_url = repo_part.strip()
 
+        # SCP syntax (git@host:path) uses ':' as the path separator, so it
+        # cannot carry a port.  Detect when the first segment is a valid TCP
+        # port number (1-65535) and raise an actionable error instead of
+        # silently misparsing the port as part of the repo path.
+        segments = repo_url.split("/", 1)
+        first_segment = segments[0]
+        if re.fullmatch(r"[0-9]+", first_segment):
+            port_candidate = int(first_segment)
+            if 1 <= port_candidate <= 65535:
+                remaining_path = segments[1] if len(segments) > 1 else ""
+                if remaining_path:
+                    git_suffix = ".git" if had_git_suffix else ""
+                    ref_suffix = f"#{reference}" if reference else ""
+                    alias_suffix = f"@{alias}" if alias else ""
+                    suggested = f"ssh://git@{host}:{port_candidate}/{remaining_path}{git_suffix}{ref_suffix}{alias_suffix}"
+                    raise ValueError(
+                        f"It looks like '{first_segment}' in 'git@{host}:{repo_url}' "
+                        f"is a port number, but SCP-style URLs (git@host:path) cannot "
+                        f"carry a port. Use the ssh:// URL form instead:\n"
+                        f"  {suggested}"
+                    )
+                else:
+                    raise ValueError(
+                        f"It looks like '{first_segment}' in 'git@{host}:{first_segment}' "
+                        f"is a port number, but no repository path follows it. "
+                        f"SCP-style URLs (git@host:path) cannot carry a port. "
+                        f"Use the ssh:// URL form: ssh://git@{host}:{port_candidate}/<owner>/<repo>.git"
+                    )
+
         # Security: reject traversal sequences in SSH repo paths
         validate_path_segments(
             repo_url, context="SSH repository path", reject_empty=True
diff --git a/tests/unit/test_generic_git_urls.py b/tests/unit/test_generic_git_urls.py
index 76d8acdc1..0fca7d9f9 100644
--- a/tests/unit/test_generic_git_urls.py
+++ b/tests/unit/test_generic_git_urls.py
@@ -781,3 +781,118 @@ def test_https_nested_group_with_virtual_ext_rejected(self):
         """HTTPS URLs can't embed virtual paths even with nested groups."""
         with pytest.raises(ValueError, match="virtual file extension"):
             DependencyReference.parse("https://gitlab.com/group/subgroup/file.prompt.md")
+
+
+class TestSCPPortDetection:
+    """Detect port-like first path segment in SCP shorthand (git@host:port/path).
+
+    SCP shorthand uses ':' as the path separator and cannot carry a port.
+    When the first path segment is a valid TCP port (1-65535), APM should
+    raise a ValueError with an actionable suggestion to use ssh:// instead.
+    """
+
+    def test_scp_with_port_7999_raises(self):
+        """Bitbucket Datacenter: git@host:7999/project/repo.git."""
+        with pytest.raises(ValueError, match="ssh://"):
+            DependencyReference.parse("git@bitbucket.example.com:7999/project/repo.git")
+
+    def test_scp_with_port_22_raises(self):
+        """Default SSH port 22 should still be detected."""
+        with pytest.raises(ValueError, match="ssh://"):
+            DependencyReference.parse("git@host.example.com:22/owner/repo.git")
+
+    def test_scp_with_port_65535_raises(self):
+        """Max valid TCP port should trigger detection."""
+        with pytest.raises(ValueError, match="ssh://"):
+            DependencyReference.parse("git@host.example.com:65535/owner/repo.git")
+
+    def test_scp_with_port_1_raises(self):
+        """Min valid TCP port should trigger detection."""
+        with pytest.raises(ValueError, match="ssh://"):
+            DependencyReference.parse("git@host.example.com:1/owner/repo.git")
+
+    def test_scp_with_leading_zeros_raises(self):
+        """Leading zeros: 007999 -> int 7999, still a valid port."""
+        with pytest.raises(ValueError, match="ssh://"):
+            DependencyReference.parse("git@host.example.com:007999/project/repo.git")
+
+    def test_scp_port_only_no_path_raises(self):
+        """git@host:7999 with no repo path after the port."""
+        with pytest.raises(ValueError, match="no repository path follows"):
+            DependencyReference.parse("git@host.example.com:7999")
+
+    def test_scp_port_trailing_slash_no_path_raises(self):
+        """git@host:7999/ — trailing slash but empty remaining path."""
+        with pytest.raises(ValueError, match="no repository path follows"):
+            DependencyReference.parse("git@host.example.com:7999/")
+
+    def test_scp_port_with_ref_raises_and_preserves_ref(self):
+        """Port-like segment with #ref should be caught; suggestion preserves the ref."""
+        with pytest.raises(
+            ValueError,
+            match=r"ssh://git@host\.example\.com:7999/project/repo\.git#main",
+        ):
+            DependencyReference.parse("git@host.example.com:7999/project/repo.git#main")
+
+    def test_scp_port_with_alias_raises_and_preserves_alias(self):
+        """Port-like segment with @alias should be caught; suggestion preserves the alias."""
+        with pytest.raises(
+            ValueError,
+            match=r"ssh://git@host\.example\.com:7999/project/repo\.git@my-alias",
+        ):
+            DependencyReference.parse("git@host.example.com:7999/project/repo.git@my-alias")
+
+    def test_scp_port_with_ref_and_alias_preserves_both(self):
+        """Suggestion should include both #ref and @alias when present."""
+        with pytest.raises(
+            ValueError,
+            match=r"ssh://git@host\.example\.com:7999/project/repo\.git#v1\.0@my-alias",
+        ):
+            DependencyReference.parse("git@host.example.com:7999/project/repo.git#v1.0@my-alias")
+
+    def test_suggestion_includes_git_suffix(self):
+        """When the user wrote .git, the suggestion should preserve it."""
+        with pytest.raises(
+            ValueError,
+            match=r"ssh://git@host\.example\.com:7999/project/repo\.git",
+        ):
+            DependencyReference.parse("git@host.example.com:7999/project/repo.git")
+
+    def test_suggestion_omits_git_suffix_when_absent(self):
+        """When the user omitted .git, the suggestion should not add it."""
+        with pytest.raises(ValueError) as excinfo:
+            DependencyReference.parse("git@host.example.com:7999/project/repo")
+        msg = str(excinfo.value)
+        assert "ssh://git@host.example.com:7999/project/repo" in msg
+        assert not msg.endswith(".git")
+
+    def test_port_zero_not_detected(self):
+        """Port 0 is invalid -- should NOT trigger port detection, parses as org name."""
+        dep = DependencyReference.parse("git@host.example.com:0/repo")
+        assert dep.repo_url == "0/repo"
+        assert dep.port is None
+
+    def test_port_out_of_range_not_detected(self):
+        """99999 > 65535 -- not a valid port, should NOT trigger port detection."""
+        dep = DependencyReference.parse("git@host.example.com:99999/repo")
+        assert dep.repo_url == "99999/repo"
+        assert dep.port is None
+
+    def test_normal_org_name_not_detected(self):
+        """Non-numeric org name should parse normally."""
+        dep = DependencyReference.parse("git@gitlab.com:acme/repo.git")
+        assert dep.repo_url == "acme/repo"
+        assert dep.port is None
+
+    def test_alphanumeric_first_segment_not_detected(self):
+        """'v2' is not purely numeric -- should parse normally."""
+        dep = DependencyReference.parse("git@gitlab.com:v2/repo.git")
+        assert dep.repo_url == "v2/repo"
+        assert dep.port is None
+
+    def test_ssh_protocol_with_port_still_works(self):
+        """ssh:// URL form with port must continue working (regression guard)."""
+        dep = DependencyReference.parse("ssh://git@bitbucket.example.com:7999/project/repo.git")
+        assert dep.host == "bitbucket.example.com"
+        assert dep.port == 7999
+        assert dep.repo_url == "project/repo"