Let pushes go by an HTTPS token or an SSH deploy key

The push credential is either a push-only account's token, handed to git
through a credential helper that names environment variables, never
values, or a deploy key in a short-lived ssh-agent. The remote URL
follows the credential. Configured as gitea.push_user and push_token, or
gitea.push_key.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE

tests/integration/test_gitea_live.py

@@ -5,12 +5,12 @@ Cleans up after itself (closes the PR, deletes the branch) so repeated runs
 do not silt up the sandbox.
 """
 
-import os
 import uuid
 from pathlib import Path
 
 import pytest
 
+from nisse_dev.agent import push_credential, remote_url
 from nisse_dev.config import AgentConfig
 from nisse_dev.execution import SSHHost
 from nisse_dev.git import GitError, GitRepo
@@ -31,17 +31,6 @@ def intent_for(branch: str) -> Intent:
     )
 
 
-def push_key() -> str:
-    """The sandbox's deploy key with write access: what the agent pushes with
-    (D4). NISSE_PUSH_KEY holds the private key itself (CI) or, since a .env
-    line can't hold one, the path to it (local runs)."""
-    value = os.environ.get("NISSE_PUSH_KEY", "")
-    assert value.strip(), "NISSE_PUSH_KEY is not set: the sandbox's deploy key"
-    if "PRIVATE KEY" not in value and Path(value).expanduser().is_file():
-        value = Path(value).expanduser().read_text()
-    return value if value.endswith("\n") else value + "\n"
-
-
 def test_push_open_pr_and_reconcile(
     tmp_path: Path, live_config: AgentConfig, gitea: GiteaClient, ssh_host: SSHHost
 ) -> None:
@@ -60,9 +49,10 @@ def test_push_open_pr_and_reconcile(
     assert reconcile(intent_for(branch)) is False
 
     # Pushed the way the agent does: from the build VM (here the throwaway
-    # sshd), over SSH, with the deploy key and never the API token.
-    key = push_key()
-    url = client.ssh_url(repo_path)
+    # sshd), with the push credential the config names, never the API token.
+    key = push_credential(live_config)
+    assert key is not None, "nisse-test.yaml names no push credential (D4)"
+    url = remote_url(client, repo_path, key)
     repo = GitRepo(ssh_host, tmp_path / "work", known_hosts=str(tmp_path / "kh"))
     repo.init()
     repo.configure_identity(account, f"{account}@example.test")
@@ -71,7 +61,7 @@ def test_push_open_pr_and_reconcile(
 
     pr = None
     try:
-        repo.push(url, branch, key=key)
+        repo.push(url, branch, credential=key)
         pr = client.open_pull_request(
             repo_path,
             head=branch,
@@ -89,7 +79,7 @@ def test_push_open_pr_and_reconcile(
         assert reconcile(intent_for(branch)) is True
 
         # D4 is only real if the server enforces it. The agent's own token
-        # must not be able to merge the PR it just opened, and its push key
+        # must not be able to merge the PR it just opened, and its push credential
         # must not be able to push to the protected default branch at all.
         merged = client._http.post(
             f"/repos/{repo_path}/pulls/{pr.number}/merge", json={"Do": "merge"}
@@ -99,9 +89,9 @@ def test_push_open_pr_and_reconcile(
             "the human gate"
         )
         with pytest.raises(GitError):
-            repo.push(url, "main", key=key)
+            repo.push(url, "main", credential=key)
     finally:
         if pr is not None:
             client.close_pull_request(repo_path, pr.number)
-        repo.delete_remote_branch(url, branch, key=key)
+        repo.delete_remote_branch(url, branch, credential=key)
         client.close()