feat(delegate): drive the public @uipath/delegate-stdio host [PILOT-7854]

[Mihaiii]

Issue

PILOT-7854

Warning

Breaking changes. The environment variable names stay as on main. What changes:

Before (main)	Now
npm install @uipath/delegate-sdk	npm install @uipath/delegate-stdio, a release that accepts the auth init option (1.202.1 and older ignore it, and init fails with Auth required unless a saved login exists)
DELEGATE_SDK_PATH → @uipath/delegate-sdk/dist/index.mjs	DELEGATE_SDK_PATH → @uipath/delegate-stdio/dist/delegate_stdio.mjs; any other file is an AgentConfigError
DELEGATE_SDK_NODE_MODULES → root holding @uipath/delegate-sdk	same name → root holding @uipath/delegate-stdio
agent.effort (Delegate-only field)	agent.sdk_options.effort, the key Claude Code already uses
Host env carried AUTH_TOKEN / TENANT_ID / ORG_ID / …	Removed from the host env; auth reaches the host as its auth init option on stdin

Unchanged: DELEGATE_ENV, DELEGATE_BACKEND_URL, and DELEGATE_AUTH_TOKEN / DELEGATE_TENANT_ID / DELEGATE_ORG_ID / DELEGATE_ORG_SLUG / DELEGATE_TENANT_SLUG, each with its bare spelling as a fallback.

Summary

• Replace the first-party agents/delegate/delegate_host.mjs with the @uipath/delegate-stdio host; it installs @uipath/delegate-sdk and the interop runtime itself
• Port DelegateAgent to the host's protocol: event frames, per-call usage frames, terminal result / error, destroyed
• Send auth, the org/tenant slugs, the backend URL and the env slug as init options (auth, backendUrl, env); remove the host's own names (AUTH_TOKEN, TENANT_ID, ORG_ID, ORG_LOGICAL_NAME, TENANT_NAME, BACKEND_URL) and DELEGATE_AUTH_TOKEN from its env, so agent shells cannot read the token and a stray BACKEND_URL cannot route the host
• Keep token usage and cost for the finished calls of a turn cut at max_turns or by an early stop
• Make crash retry independent of the host's stderr text (build 13599116 retried "terminated" on four tasks but not on one whose id contains "guardrail")

Changes

Adapter — src/coder_eval/agents/delegate_agent.py

• _resolve_host_bundle replaces _resolve_sdk_entry: DELEGATE_SDK_PATH, DELEGATE_SDK_NODE_MODULES, then the cwd and its ancestors, this agent's own agents/delegate/, and home
• _env (namespaced first, bare fallback) + _auth_option build the auth init option; _HOST_ENV_REMOVED lists what leaves the host env
• Read toolArgs / toolResult / toolStatus, Anthropic-convention usage, result.model; num_turns = len(result.turnUsages)
• isStepStart: false deltas extend one text block; enableSkills is sent explicitly (the host default is false)
• Sum the per-call usage frames; the result's usage (the turn total) replaces the sum
• A tool result with no open call keeps its name and args; toolStatus: "interrupted" is an error
• Categorize WAF blocks (content filter, not retried), SSE connect timeouts (connection, retried) and session conflicts (retry in a new conversation)
• Init errors: only auth / missing slugs / unknown env are non-retryable AgentConfigError (with a hint that names coder_eval's variables); other init errors and the 60 s init deadline are retryable
• No crash reason carries the stderr tail; it is logged at WARNING
• get_sdk_options() returns the init options with auth reduced to its field names and backendUrl to its host; a cancelled stdout drain no longer logs at ERROR; _force_kill_host clears the process handle
• Remove LLMGW_* from the host env when a token file is set

Docs, CI, tests

• docs/agents/DELEGATE.md, docs/USER_GUIDE.md, docs/agents/HARNESS_PARITY.md, .env.example, .claude/notes/agents.md
• pr-checks.yml delegate-live-tests: installs @uipath/delegate-stdio, sets the DELEGATE_* names from the existing DELEGATE_* secrets
• Unit-test frame builders replay shapes recorded from a live 1.202.1 transcript; an autouse fixture clears the developer's own DELEGATE_* values

Implementation Notes

• The host gives each auth field priority over its env var; the SDK reads none of them. It takes the credentials from the TokenAuthProvider the host builds, and an explicit backendUrl replaces the BACKEND_URL default its bundle reads at load. Host side: UiPath/Autopilot#6656. A refresh source (token file, LLMGW_*, saved login) still writes its token into the host's own process.env.AUTH_TOKEN.
• agents/delegate/package.json still says ^1.202.1. Raise it to the first release that carries the usage frame and the auth option (both in UiPath/Autopilot#6656); until then the live CI job installs a host that ignores auth.
• Cut-turn usage relies on frame order: call N's usage frame precedes the tool results of call N. The max_turns boundary does not move.
• max_turns stays client-side: live, maxSteps: 2 ran 7 steps.

Testing

• test_delegate_agent*.py, test_delegate_agent_config.py, test_error_handling.py: 195 passed, 6 skipped. New tests: the auth option, namespaced-over-bare, removed host names, redacted sdk_options, the DELEGATE_SDK_PATH file check, the init-error hint, stderr-tail categorization, init retry, drain cancel, kill() handle
• Each review-fix test failed on the previous adapter code and passes now
• Live against alpha, host built from UiPath/Autopilot#6656, DELEGATE_STDIO_VERBOSE=1: PONG, 12,250 tokens, $0.00095; the host log shows Using init-option / env var auth (not the saved login); the token is in neither the host's stderr nor sdk_options
• Full suite: 5840 passed, coverage 88.17 %; custom lint (735), ruff, prose budget, pyright on the adapter clean. The 20 other local failures (Windows symlink privilege, missing litellm, a node_modules in a parent of the temp dir) are environment-only

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