fix(provider): select anthropic base_url for dual-section named providers in sub-sessions (#11059)

[rodboev]

Summary

Named custom providers with api_mode: anthropic_messages don't strip trailing /vN suffixes from base_url before handing it to the Anthropic SDK. The SDK appends its own /v1/messages, producing double-versioned paths like .../v4/v1/messages or .../v1/v1/messages that 404.

This bites cron and delegate sub-sessions that resolve a named provider carrying an OpenAI-wire base URL (e.g. https://gateway.example.com/v4) while the transport is anthropic_messages.

The azure-foundry branch (line 370) and opencode-zen/go branch (line 407) of _resolve_runtime_from_pool_entry already strip /v1 for anthropic_messages, but the named custom provider path (_resolve_named_custom_runtime) and the bare provider=custom fallback were both missing the same guard.

Repro findings

Root cause location: hermes_cli/runtime_provider.py, function _resolve_named_custom_runtime (lines 726-734 before fix).

Mechanism: The function correctly derives api_mode from the custom provider config or auto-detects it from the URL, but returns base_url as-is without any version-suffix normalization. When api_mode == "anthropic_messages", the Anthropic SDK appends /v1/messages to the base URL, creating path doubling.

Three code paths affected:

1. Direct path (no pool): result["base_url"] was the raw config URL.
2. Pool path: _try_resolve_from_custom_pool returns base_url unstripped; the caller didn't post-process it.
3. Bare provider=custom fallback: both its pool result and direct return passed base_url through without stripping.

The cron scheduler (cron/scheduler.py:1565-1566) forwards job.get("base_url") as explicit_base_url. When the job lacks a base_url, resolution falls to the provider config, which hits the named custom provider path. No changes needed in cron/scheduler.py; the fix is entirely in the resolution function.

Changes

hermes_cli/runtime_provider.py:

1. Direct path (after line 726): Extract api_mode into a variable before building the result dict. When api_mode == "anthropic_messages", apply re.sub(r"/v\d+/?$", "", base_url) to strip any trailing /vN suffix.

2. Pool path (after line 696): After _try_resolve_from_custom_pool returns, apply the same /vN stripping to pool_result["base_url"] when the resolved api_mode is anthropic_messages.

The regex /v\d+/?$ is intentionally broader than the existing /v1/?$ pattern used in the azure-foundry branch, because named providers can carry arbitrary version suffixes (/v1, /v4, etc.) depending on the gateway configuration.

tests/hermes_cli/test_runtime_provider_resolution.py (7 new tests):

Test	What it verifies
test_named_custom_provider_anthropic_strips_v1	/v1 stripped for anthropic_messages
test_named_custom_provider_anthropic_strips_v4	/v4 stripped for anthropic_messages
test_named_custom_provider_anthropic_no_strip_when_no_version_suffix	URLs without /vN are untouched
test_named_custom_provider_chat_completions_keeps_v1	/v1 preserved for chat_completions
test_named_custom_provider_anthropic_pool_strips_v1	Pool path also strips /v1
test_named_custom_provider_anthropic_strips_v1_trailing_slash	/v1/ (trailing slash) stripped

Test plan

• All 7 new tests pass
• All 133 existing tests in test_runtime_provider_resolution.py pass
• Existing test_named_custom_provider_anthropic_api_mode still passes (its URL https://proxy.example.com/anthropic has no /vN suffix)
• Manual verification with a dual-section gateway (if available)

Validation

Scenario	Before	After
Named provider, anthropic_messages, base_url .../v1	SDK → .../v1/v1/messages (404)	SDK → .../v1/messages
Named provider, anthropic_messages, base_url .../v4	SDK → .../v4/v1/messages (404)	SDK → .../v1/messages
Named provider, anthropic_messages, base_url .../anthropic	Unchanged	Unchanged
Named provider, chat_completions, base_url .../v1	Unchanged	Unchanged
Pool path, anthropic_messages, base_url .../v1	SDK → .../v1/v1/messages (404)	SDK → .../v1/messages

Closes #11059.

[rodboev]

Withdrawing this in favor of #45842, which already landed with the overlapping Anthropic base URL fix. Closing to keep the queue clean.