gateway: put audio pricing on the shared cost-map key (no SpendLogs row at all)

The first audio deploy proved the config and the cost-calculator patch were both
live — /model/info served input_cost_per_request, and the build log confirmed
'[coop-patch] applied' — yet a real /v1/audio/speech and
/v1/audio/transcriptions pair still billed exactly $0.000000, with no spend row
anywhere. Diagnosis: the audio cost paths resolve pricing from the SHARED
cost-map key, and the router strips per-deployment pricing from that key, so the
lookup raises and the spend write is skipped. Same mechanism as the
image-generation case patch_image_cost.py already fixes.

The cost-calculator patch cannot cover this on its own: it adds a per-request
charge on top of a cost the normal path computes, and that path never got there.

This patch re-adds the pricing for audio_speech and audio_transcription
deployments, explicitly allowing input_cost_per_request through — LiteLLM does
not list it among its CustomPricing fields, which is precisely why the
cost-calculator patch has to read it.

patch_audio_router_pricing.py

@@ -0,0 +1,112 @@
+"""Keep audio-model pricing on the shared cost-map key (speech + transcription).
+
+Run at BUILD time (the runtime rootfs is read-only under Cloudron). Non-fatal:
+if the target file or the anchor is missing — e.g. after a version bump — it
+prints a warning and exits 0, so the build and the gateway still succeed. Look
+for the ``[coop-patch]`` line in the build log.
+
+Why this is needed on top of patch_audio_request_cost.py: the audio cost paths
+(speech, transcription) resolve pricing from the **shared** cost-map key, and the
+router deliberately strips per-deployment pricing from that key ("so one
+deployment's overrides don't pollute sibling deployments"). For a deployment on a
+custom backend — ours are all `openai/<model>` against a local Tinfoil proxy —
+the cost lookup then raises, the spend-log write is skipped, and **no SpendLogs
+row appears at all**. That is the symptom we measured: `/v1/audio/speech` and
+`/v1/audio/transcriptions` returned 200 with real audio, and the member key's
+spend stayed exactly $0.000000 with no spend row anywhere. It is the same
+mechanism as the image-generation case that patch_image_cost.py already fixes
+(upstream BerriAI/litellm#10023/#12471).
+
+The cost-calculator patch alone cannot fix it: it only adds a per-request charge
+*on top of* a cost the normal path computed, and that path never got that far.
+
+`input_cost_per_request` is deliberately allowed through even though it is **not**
+in `CustomPricingLiteLLMParams.model_fields` — LiteLLM does not list it there, and
+patch_audio_request_cost.py is what makes the cost calculator read it.
+
+Safe for us: the co-op gateway has one deployment per audio backend, so there are
+no sibling deployments for the shared key to pollute.
+"""
+from __future__ import annotations
+
+import glob
+import os
+import sys
+
+MARKER = "CO-OP PATCH (audio shared pricing, 2026-10-26)"
+
+ANCHOR = "        # Always register the (possibly mode-preserved) shared backend info."
+
+INSERT = '''        # CO-OP PATCH (audio shared pricing, 2026-10-26): the audio cost paths
+        # (speech, transcription) read pricing from the shared cost-map key, and
+        # this router strips per-deployment pricing from it — so a custom-backend
+        # audio deployment raises in the cost lookup, the spend write is skipped,
+        # and no SpendLogs row appears at all (same mechanism as the image case
+        # this file already patches). Re-add the pricing for audio modes,
+        # including input_cost_per_request, which LiteLLM does not list among its
+        # CustomPricing fields.
+        if deployment_mode in ("audio_speech", "audio_transcription"):
+            for _ak, _av in model_info.items():
+                if (
+                    _ak in CustomPricingLiteLLMParams.model_fields
+                    or _ak == "input_cost_per_request"
+                ) and _av is not None:
+                    shared_model_info[_ak] = _av
+
+'''
+
+
+def target_path() -> str:
+    if len(sys.argv) > 1:
+        return sys.argv[1]
+    env = os.environ.get("LITELLM_ROUTER")
+    if env:
+        return env
+    hits = []
+    try:  # most reliable: ask the installed package where it lives
+        import litellm  # noqa: PLC0415
+        _file = getattr(litellm, "__file__", None)
+        if _file:
+            hits.append(os.path.join(os.path.dirname(_file), "router.py"))
+    except Exception:
+        pass
+    hits += glob.glob("/app/.venv/lib/python*/site-packages/litellm/router.py")
+    hits += glob.glob("/usr/local/lib/python3*/site-packages/litellm/router.py")
+    hits = [h for h in hits if os.path.exists(h)]
+    if not hits:
+        raise SystemExit("[coop-patch] could not locate litellm/router.py")
+    return sorted(hits)[0]
+
+
+def main() -> int:
+    path = target_path()
+    try:
+        source = open(path).read()
+    except OSError as exc:
+        print(f"[coop-patch] cannot read {path}: {exc}")
+        return 0
+
+    if MARKER in source:
+        print(f"[coop-patch] {path} already patched, nothing to do")
+        return 0
+
+    if ANCHOR not in source:
+        print(f"[coop-patch] WARNING anchor not found in {path}; audio pricing will "
+              f"NOT reach the shared cost map and audio spend will stay invisible")
+        return 0
+
+    patched = source.replace(ANCHOR, INSERT + ANCHOR, 1)
+    compile(patched, path, "exec")  # refuse to write something that will not import
+
+    if not os.access(path, os.W_OK):  # practice run against a read-only copy
+        print(f"[coop-patch] {path} is not writable; verified anchor and syntax only")
+        return 0
+
+    with open(path, "w") as handle:
+        handle.write(patched)
+    print(f"[coop-patch] applied audio shared pricing to {path}")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())