fix(providers): stop zed-hosted claude-haiku-4-5 thinking from inflating max_tokens (#13364)

[diegosouzapw]

Closes #13364

Root cause (short)

zed-hosted's passthrough catalog exposes the short hyphenated Claude id
claude-haiku-4-5, but modelSpecs' registered alias for that model is the dotted
claude-haiku-4.5 — a spelling mismatch, not a missing spec. Because
PROVIDER_MODEL_ALIASES had no zed-hosted entry, resolveCanonicalProviderModel
passed the wire id through unchanged, so getCanonicalModelSpecId found neither an
exact nor an alias match. capMaxOutputTokens() then resolved null, and
fitThinkingToMaxTokens took the "no known cap" branch — adding the response
headroom directly to the requested thinking budget instead of fitting under the
real ceiling: 32000 + 131072 = 163072, which Zed's proxy rejects (model's real
output cap is 64000). The codebase already has the identical fix for the same
class of provider (kiro, in the same PROVIDER_MODEL_ALIASES table) — zed-hosted
never got the equivalent entry.

Fix

Add a zed-hosted entry to PROVIDER_MODEL_ALIASES in open-sse/services/model.ts,
mapping claude-haiku-4-5 → claude-haiku-4.5, same pattern as the existing kiro
entry. Scoped to claude-haiku-4-5 only (the model reported and reproduced) — not
guessing at Sonnet/Opus id spellings on Zed without confirming them against the live
catalog first.

This only affects capability/budget-cap lookups
(resolveCanonicalProviderModel → getStaticSpec/capMaxOutputTokens). It never
touches the wire model field sent to Zed: zed-hosted.ts passes the raw wire model
string straight into openaiToClaudeRequest(model, ...), and result.model = model
is set unconditionally from that same raw string, never rewritten by the alias table.

Regression test

tests/unit/issue-13364-zed-hosted-haiku-thinking-inflation.test.ts

Run:

DATA_DIR=$(mktemp -d) timeout 300 node --import tsx/esm --test --test-force-exit \
  tests/unit/issue-13364-zed-hosted-haiku-thinking-inflation.test.ts

Before fix (RED) — matches the reporter's live-proxy numbers exactly:

✖ zed-hosted/claude-haiku-4-5 thinking+tools must not inflate max_tokens past the real 64000 output cap
  AssertionError: max_tokens (163072) must not exceed the model's real output cap (64000) — Anthropic/Zed rejects the request otherwise

After fix (GREEN):

✔ zed-hosted/claude-haiku-4-5 thinking+tools must not inflate max_tokens past the real 64000 output cap (89.286607ms)
ℹ pass 1
ℹ fail 0

Gates run

• npx eslint --suppressions-location config/quality/eslint-suppressions.json open-sse/services/model.ts tests/unit/issue-13364-zed-hosted-haiku-thinking-inflation.test.ts → clean, no warnings.
• npm run check:open-sse-typecheck → clean.
• node scripts/check/check-file-size.mjs → no new violations on touched files.
• node scripts/check/check-complexity.mjs / node scripts/check/check-cognitive-complexity.mjs → no new violations (additive data-table change only).
• node scripts/check/check-test-discovery.mjs → new test file discovered.
• Existing related suites, all green:
  tests/unit/kiro-claude-sonnet-5-2267.test.ts, tests/unit/zed-provider.test.ts,
  tests/unit/zed-hosted-proxy-enums-13362.test.ts,
  tests/unit/zed-hosted-think-close-marker.test.ts,
  tests/unit/zed-hosted-models-discovery-route.test.ts,
  tests/unit/zed-hosted-loopback-port-derivation.test.ts,
  tests/unit/zed-hosted-stream-error-boundary.test.ts (this one timed out once under
  heavy machine load running alongside the other 6 files; re-run in isolation passed
  cleanly in 46s — a load-related flake, unrelated to this change, which only touches
  open-sse/services/model.ts).

Existing tests aligned

None — no existing assertion encoded the old buggy contract; this is a purely additive
lookup-table entry.

Not covered here

• The broader effortBudgetMap.high = 131072 behavior (any reasoning_effort above
  medium maps straight to Anthropic's xhigh-tier thinking budget) affects every
  provider through this translation leg, not just zed-hosted, and is out of scope for
  this fix.
• Sonnet/Opus ids on zed-hosted are not added here — only claude-haiku-4-5 is
  reproduced/reported. A follow-up should confirm the live Zed catalog spelling before
  adding those.