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Add AI agent detection to user-agent string#701

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simonfaltum/agent-detection
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Add AI agent detection to user-agent string#701
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simonfaltum/agent-detection

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@simonfaltum simonfaltum commented Mar 12, 2026 •
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Summary

  • Detect known AI coding agents via environment variables and append agent/<name> to the HTTP user-agent header
  • Canonical agent list: Antigravity (ANTIGRAVITY_AGENT), Claude Code (CLAUDECODE), Cline (CLINE_ACTIVE), Codex (CODEX_CI), Copilot CLI (COPILOT_CLI), Cursor (CURSOR_AGENT), Gemini CLI (GEMINI_CLI), OpenCode (OPENCODE)
  • Returns empty string when zero or multiple agents are detected (ambiguity guard)
  • Uses the same double-checked locking pattern as existing CI/CD detection
  • Part of a cross-SDK effort (Go SDK PR #1537, Python SDK PR #1327)

The COPILOT_CLI env var was confirmed by direct testing in Copilot CLI.

Test plan

  • Unit test for each of the 8 agents individually
  • Test: no agent env vars set produces no agent/ segment
  • Test: multiple agent env vars set produces no agent/ segment
  • Test: empty env var value produces no agent/ segment
  • Test: cached value persists after environment change
  • mvn spotless:apply passes
  • mvn -Dtest=UserAgentTest test passes

This pull request was AI-assisted by Isaac.

@simonfaltum
Add AI agent detection to user-agent string
4c3b838 
Detect known AI coding agents (Claude Code, Cursor, Cline, Codex,
Gemini CLI, OpenCode, Antigravity) via environment variables and
append agent/<name> to the user-agent header. Uses the same
double-checked locking pattern as CI/CD detection. Returns empty
when zero or multiple agents are detected (ambiguity guard).

Co-authored-by: Isaac
@simonfaltum
Use @AfterEach for test cleanup instead of manual calls
5c3a1a5 
Move cleanupAgentEnv() to an @AfterEach tearDown method so test
isolation is failure-safe. Previously, if an assertion failed before
the manual cleanup call, static state would leak between tests.

Co-authored-by: Isaac
simonfaltum
simonfaltum commented Mar 12, 2026
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Review (automated, 2 agents)

Verdict: Approved

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

See inline comments for details.

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simonfaltum commented Mar 12, 2026

[Gap (Nit)] Existing cicd tests now depend on @AfterEach for agentProvider reset

The PR removes manual UserAgent.env = null cleanup from the three existing cicd tests and relies on @AfterEach. The cicd tests' setup doesn't reset agentProvider, creating implicit coupling.

Suggestion: Add UserAgent.agentProvider = null to existing cicd tests' setup for consistency.

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simonfaltum commented Mar 12, 2026

[Gap (Nit)] Missing test that cicd and agent coexist in user-agent string

The PR adds agent detection alongside CI/CD detection, but no test asserts both segments are present together.

Suggestion: Add a test with one CI/CD env var and one agent env var set, then assert both cicd/... and agent/... appear.

@simonfaltum
Address review feedback: AgentDef class, early exit, null check
6f6ebb8 
Replace AbstractMap.SimpleEntry with AgentDef inner class to match
the CicdProvider/EnvVar style. Add early exit in lookupAgentProvider
when count > 1. Remove redundant null check for agentProvider()
return value to match cicdProvider() pattern.

Co-authored-by: Isaac
@simonfaltum simonfaltum marked this pull request as ready for review March 12, 2026 13:56
@simonfaltum
Add Copilot CLI to agent detection
d709d85 
We have data from direct testing in Copilot CLI confirming it sets
COPILOT_CLI=1 in its environment. Add it to the canonical agent list.

Co-authored-by: Isaac
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github-actions bot commented Mar 13, 2026

If integration tests don't run automatically, an authorized user can run them manually by following the instructions below:

Trigger:
go/deco-tests-run/sdk-java

Inputs:

  • PR number: 701
  • Commit SHA: 9fd21275fae65449f15e77ecd515ff982d677cab

Checks will be approved automatically on success.

@simonfaltum simonfaltum deployed to test-trigger-is March 13, 2026 16:15 — with GitHub Actions Active
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