feat(combo): add agentic-stall response classifier

.env.example

@@ -770,6 +770,13 @@ ALLOW_API_KEY_REVEAL=false
 # Validated to >= 1, clamped to <= 32.  |  Default: 3
 # COMBO_CONCURRENCY_PER_MODEL=3
 
+# Agentic-stall response classifier (opt-in, default OFF).
+# Used by: open-sse/services/combo/agenticStall.ts — classifies a combo member's
+# "finish: stop + narration + zero tool calls" answer to a tool-result turn as a
+# stall. Classification only for now: no combo call site consumes the verdict yet.
+# Set to 1 (or true) to enable.  |  Default: false
+# OMNIROUTE_AGENTIC_STALL_FAILOVER=false
+
 # Disable conversation-history tracking (#13150).
 # Used by: open-sse/services/conversationTracker.ts. resolveConversationId()
 # returns an untracked result before it reads SQLite or parses message history,

changelog.d/features/13954-agentic-stall-classifier.md

@@ -0,0 +1 @@
+- **feat(combo):** add the agentic-stall response classifier (`open-sse/services/combo/agenticStall.ts`) — flags a `finish: stop` + narration + zero-tool-call answer to a tool-result turn. Opt-in via `OMNIROUTE_AGENTIC_STALL_FAILOVER=1` (default OFF); classification only, no combo call site yet ([#13954](https://github.com/cheaper-inference/OmniRoute/pull/13954) - thanks @patrykkopycinski)

docs/reference/ENVIRONMENT.md

@@ -321,6 +321,7 @@ OmniRoute provides a two-layer defense: request-side injection scanning and resp
 | `OMNIROUTE_REDACT_THINKING`                                 | `true`                       | `open-sse/executors/base/redactThinkingBeta.ts` | Set `false` to stop OmniRoute adding the `redact-thinking-2026-02-12` Anthropic beta itself (empty signature-only thinking blocks). Requests with `thinking.display: "summarized"` skip it regardless; a client-negotiated redact beta or a CC-compatible `requestDefaults.redactThinking` opt-in keeps it. Claude OAuth requests keep the beta (it is part of the Claude Code OAuth fingerprint) unless the default-off `CLAUDE_OAUTH_SUMMARIZED_THINKING_UNREDACTED` feature flag is on.                                    |
 | `BARE_MODEL_DEFAULT_OVERRIDE_LEGACY`                        | `false`                      | `open-sse/services/model.ts`                    | Legacy `resolveBareModelToConnectionDefault` behaviour (#4825): replace any bare model name with the selected connection's `defaultModel`. Off by default, only `auto` or an empty model is replaced; logs one warning per pair when on.                                                                                                                                                                                                                                                                                      |
 | `COMBO_CONCURRENCY_PER_MODEL`                               | `3`                          | `open-sse/services/comboConfig.ts`              | Per-model concurrency cap for round-robin combos (#9100). The round-robin combo semaphore was hard-capped at 3 concurrent requests per model with no override, serializing higher-concurrency traffic behind that cap. Validated to `>= 1`, clamped to `<= 32`.                                                                                                                                                                                                                                                               |
+| `OMNIROUTE_AGENTIC_STALL_FAILOVER`                          | `false`                      | `open-sse/services/combo/agenticStall.ts`       | Opt-in: set to `1` (or `true`) to enable the agentic-stall response classifier, which flags a combo member's `finish: stop` + narration + zero-tool-call answer to a tool-result turn as a stall. Default OFF. Classification only for now — no combo call site consumes the verdict yet.                                                                                                                                                                                                                                     |
 | `DISABLE_CONTEXT_WINDOW_CHECKS`                             | `false`                      | `open-sse/handlers/chatCore.ts`                 | Dangerous opt-in that skips OmniRoute's local context-window / max-input-token check for direct single-model requests. Upstream providers still enforce their actual limits; prompt compression and the model's own output-token cap remain active. Effective precedence is Feature Flags DB override > environment variable > default; no restart is required.                                                                                                                                                               |
 | `OMNIROUTE_SELF_HOSTED_PROVIDERS`                           | _(unset)_                    | `open-sse/services/selfHostedEntry.ts`          | Inline YAML `providers:` document (RIC-738, D4). When set (with or without a `strategy:` block), `/v1/chat/completions` diverts to the self-hosted unified OpenAI-compatible entry instead of the cloud pipeline. Unset (the default): the route falls straight through to the existing cloud pipeline. See `docs/routing/SELF_HOSTED_OPENAI_ENTRY.md`.                                                                                                                                                                       |
 | `OMNIROUTE_SELF_HOSTED_PROVIDERS_FILE`                      | _(unset)_                    | `open-sse/services/selfHostedEntry.ts`          | Path to a YAML file holding the same `providers:` document as `OMNIROUTE_SELF_HOSTED_PROVIDERS`, for deployments that prefer a file over an inline env var. Either one activates the self-hosted entry.                                                                                                                                                                                                                                                                                                                       |