Add AI agent detection to user-agent string

[simonfaltum]

Summary

• Detect known AI coding agents via environment variables and append agent/<name> to the User-Agent HTTP header
• Canonical agent list (synced with Go SDK): Antigravity, Claude Code, Cline, Codex, Copilot CLI, Cursor, Gemini CLI, OpenCode, OpenClaw
• Ambiguity guard: reports only when exactly one agent is detected, returns empty on zero or multiple matches

The COPILOT_CLI env var was confirmed by direct testing in Copilot CLI.
The OPENCLAW_SHELL env var uses context-qualified values (exec, acp, acp-client); any non-empty value triggers detection.

Part of cross-SDK agent tracking effort. Go SDK implementation: databricks/databricks-sdk-go#1537.

Test plan

• 14 new agent detection tests (each agent individually, no agent, multiple agents, empty value, UA string inclusion/exclusion)
• Existing CI/CD and user-agent tests still pass
• Cache resets updated in test_config.py and test_core.py to prevent cross-test contamination

[simonfaltum]

Review (automated, 2 agents)

Verdict: Approved

0 Critical | 0 Major | 1 Gap | 2 Nit | 2 Suggestion

See inline comments for details.

[simonfaltum]

[Gap (Nit)] No test for to_string() with multiple agents

There are tests for to_string() with one agent and zero agents, and a unit test for agent_provider() returning "" with multiple agents. But there's no end-to-end test confirming to_string() excludes agent/ when multiple agents are set. Coverage gap is marginal since if agent: on "" is trivially falsy.

Suggestion: Add test_user_agent_string_multiple_agents that sets two agent vars and asserts "agent/" not in ua. Low priority.

[simonfaltum]

[Nit] Fixture name clear_cicd is misleading

This fixture now resets both _cicd_provider and _agent_provider, and its comments say "Clear cached CICD and agent providers." The name no longer reflects its scope.

Suggestion: Rename to clear_ua_caches or clean_useragent_env.

[simonfaltum]

[Nit] Unrelated formatting changes bundled in the PR

This file and similar changes in test_config.py and test_core.py include cosmetic reformatting of multi-line string arguments unrelated to agent detection. Makes the diff noisier.

Suggestion: Consider splitting formatting changes into a separate commit, or note them in the PR description.

[simonfaltum]

[Suggestion] Fixture teardown os.environ restore is a correctness improvement worth noting

The old os.environ = original_env replaced the os._Environ mapping object with a plain dict (from .copy()), subtly breaking os.putenv sync. The new .clear() + .update() approach correctly modifies the mapping in place. This is a genuine fix.

Suggestion: Worth calling out in the PR description as an intentional fix so reviewers don't mistake it for a no-op refactor.

[simonfaltum]

Saw this build / fmt error

Run git diff --exit-code
diff --git a/tests/integration/test_auth.py b/tests/integration/test_auth.py
index be30922..ba5c42e 100644
--- a/tests/integration/test_auth.py
+++ b/tests/integration/test_auth.py
@@ -138,11 +138,13 @@ def _test_runtime_auth_from_jobs_inner(w, env_or_skip, random, dbr_versions, lib
 
     my_name = w.current_user.me().user_name
     notebook_path = f"/Users/{my_name}/notebook-native-auth"
-    notebook_content = io.BytesIO(b"""
+    notebook_content = io.BytesIO(
+        b"""
 from databricks.sdk import WorkspaceClient
 w = WorkspaceClient()
 me = w.current_user.me()
-print(me.user_name)""")
+print(me.user_name)"""
+    )
 
     from databricks.sdk.service.workspace import Language
 
diff --git a/tests/test_config.py b/tests/test_config.py
index c95e3ce..7a2286d 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -137,7 +137,8 @@ def write_large_dummy_executable(path: pathlib.Path):
 
     # Generate a long random string to inflate the file size.
     random_string = "".join(random.choice(string.ascii_letters) for i in range(1024 * 1024))
-    cli.write_text("""#!/bin/sh
+    cli.write_text(
+        """#!/bin/sh
 cat <<EOF
 {
 "access_token": "...",
@@ -146,7 +147,9 @@ cat <<EOF
 }
 EOF
 exit 0
-""" + random_string)
+"""
+        + random_string
+    )
     cli.chmod(0o755)
     assert cli.stat().st_size >= (1024 * 1024)
     return cli
diff --git a/tests/test_core.py b/tests/test_core.py
index 604e175..2e64a15 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -85,7 +85,8 @@ def write_large_dummy_executable(path: pathlib.Path):
 
     # Generate a long random string to inflate the file size.
     random_string = "".join(random.choice(string.ascii_letters) for i in range(1024 * 1024))
-    cli.write_text("""#!/bin/sh
+    cli.write_text(
+        """#!/bin/sh
 cat <<EOF
 {
 "access_token": "token",
@@ -94,7 +95,9 @@ cat <<EOF
 }
 EOF
 exit 0
-""" + random_string)
+"""
+        + random_string
+    )
     cli.chmod(0o755)
     assert cli.stat().st_size >= (1024 * 1024)
     return cli
Error: Process completed with exit code 1.

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• PR number: 1327
• Commit SHA: c49bad8474c03245995ec1bfc29cdafbf9323a2a

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