fix(params): send keyterm, not keyterms — and stop silently dropping 6 more params

[Jacob-Lasky]

Streaming is broken in production for seven real Deepgram parameters. This fixes that, and adds the wire-level test that would have caught it.

The bug

Reported live:

AsyncV1Client.connect() got an unexpected keyword argument 'keyterms'

Deepgram's parameter is the singular keyterm, repeated once per term. The frontend models it as a plural list and its URL preview translated correctly — which is why the displayed URL looked right — but the request path forwarded the internal plural name verbatim.

It failed two different ways, and the quiet one is worse:

• Streaming raised TypeError before any network call, killing the stream.
• Batch silently ignored it. Deepgram drops unknown query params without erroring, so scripts/test_rrhaphy_keyterms.py ran its "WITH keyterms" arm with no keyterms applied at all. That comparison was no-keyterms against no-keyterms. Those CSVs are void, and "keyterms don't help" was never testable from them.

Fixed at the single parameter gate (PARAM_ALIASES), so every call site — streaming, batch, raw, URL builder — is corrected at once.

Six more params were already broken the same way

deepgram-sdk enumerates only ~28 of Deepgram's query params as keyword arguments and raises TypeError on anything else. A guard test comparing our emitted params against the SDK's actual signature found six more the UI exposes and the SDK does not name:

filler_words, no_delay, word_confidence, alternatives, diarize_version, entity_prompt

_params_to_sdk_kwargs now splits params into named kwargs and RequestOptions.additional_query_parameters. The accepted-name set is computed from the installed SDK, never hardcoded, so it widens on its own when a newer SDK starts naming them.

Terminology, corrected with teeth

keyterm and keywords are different features, not two names for one thing:

• Keyterm Prompting (keyterm, Nova-3 and Flux) improves Keyword Recall Rate and takes bare terms only. No intensifier syntax — keyterm=term:2 prompts for the literal string term:2.
• Keywords (keywords, Nova-2 and older) is the boosting feature, keywords=TERM:INTENSIFIER.

Verified against deepgram-docs fern/pages/speech-to-text/custom-vocabulary/{keyterm,keywords}.mdx. The weight syntax had leaked onto keyterms in a test fixture (keyterms: ["hello:2", "world"]) and a harness comment called it "intensifier boost", so anyone copying that pattern silently got a useless term.

keywords is dropped entirely: this app targets Nova-3 and Flux, and a Nova-2-only param in the params panel invites sending it on a Nova-3 request, where Deepgram ignores it silently and the user concludes the feature is broken. Removed from config/defaults.json, the Alpine state, and the template, and added to DENIED_PARAMS so it cannot arrive via extra either.

Two more defects found in review

• Alias collisions silently dropped a value. Two sources can reach one wire param at once: the UI's plural keyterms and an explicit extra={"keyterm": ...}. A plain assignment kept whichever came last in dict order. Repeatable params are now unioned, order-preserving and deduped. Single-valued params still take one value, because unioning model would put a list where a string belongs.
• The deny list was enforced on the caller's param name, not the wire name. No live bypass existed, since no alias currently targets a denied param, but the invariant was unguarded. _is_blocked() now checks both names, and a test monkeypatches an alias onto callback to guard the invariant rather than today's alias table.

Live verification

tests/test_wire_contract.py is new and is the point of this PR. It stands up a real WebSocket server on loopback, points the SDK's environment at it, and asserts on the request path the SDK actually sent. Every other test here checks the dict we hand the SDK — the producer half only. The SDK could accept a kwarg and drop it and nothing would notice, which is exactly how this bug survived: present in our dict, absent on the wire. No Deepgram credential required.

Observed handshake path:

/v1/listen?keyterm=alpha+beta&keyterm=gamma&model=nova-3&tag=t1&tag=t2
  &filler_words=true&no_delay=true&word_confidence=true
  &alternatives=3&diarize_version=v2&entity_prompt=names

Repro proof. These tests were confirmed to fail on the pre-fix code, with the reported symptom rather than an adjacent one:

TypeError: AsyncV1Client.connect() got an unexpected keyword argument 'keyterms'
TypeError: AsyncV1Client.connect() got an unexpected keyword argument 'filler_words'

11 tests fail with the alias and the kwarg split reverted; all pass with them restored. The helper deliberately re-raises TypeError instead of swallowing it, so a regression names the user's error instead of "server never saw a handshake".

UI artifact. Playwright against the running app confirms the Keywords field is gone — no rendered label, no x-model binding, and no keywords key in the live Alpine params state — with zero console errors. The URL preview emits keyterm=perineorrhaphy&keyterm=cerebral%20palsy: singular, repeated per term, multi-word phrase preserved as one term.

That probe is committed as scripts/probe_ui.py so the next UI change doesn't re-invent it, and it exits non-zero on unmet expectations rather than just printing a screenshot.

Still unverified: no real-wire call to Deepgram itself. The key-mint API returned 503 while this was being built, so the six passthrough params are proven to reach the URL but not proven accepted by Deepgram's server. Worth one live run after merge.

104 passed, 1 skipped.