🔴 P0 (Critical) — verified at source, must fix

SEA is non-functional on a clean install: the generated loader requires package names that are garbled AND undeclared in optionalDependencies.
native/sea/index.js (all platform branches) + package.json

I confirmed both halves:

• Every npm fallback in the loader is @databricks/sea-native-linux-x64-gnu- — e.g. ...-gnu-darwin-arm64, ...-gnu-win32-x64-msvc, and even the real linux target resolves to
  @databricks/sea-native-linux-x64-gnu-linux-x64-gnu. The M0 triple linux-x64-gnu got baked into the package prefix for every platform — a napi-rs npmName misconfiguration when index.js was regenerated.
• optionalDependencies contains only lz4 and @napi-rs/cli — none of the per-platform native packages. So npm install never fetches a .node, and a useSEA:true caller always hits MODULE_NOT_FOUND, on every
  platform including the supported one.

→ Fix: regenerate native/sea/index.js with the correct npmName, declare the real per-platform packages in optionalDependencies, and align the loader hint / .npmignore comments to that name. Add a test
asserting the require name in index.js matches an optionalDependencies key. (Also: @napi-rs/cli is a build tool sitting in optionalDependencies — it'll be pulled into consumer installs; belongs in
devDependencies.)

🟠 P1 (Important)

1. M2M-vs-U2M flow selection diverges from Thrift and breaks a valid config (carryover Simplify basic usage (hide Thrift details) #1 from [SEA-NodeJS] (8/8) M1 Phase 1 — OAuth M2M + OAuth U2M (5 review rounds, ZERO HIGH at close) #383 — PERSISTS, and it's a real trap, not just a comment) — SeaAuth.ts:270-316. Thrift keys off the secret
   (oauthClientSecret === undefined ? U2M : M2M, DBSQLClient.ts:216); SEA selects M2M whenever oauthClientId is present. A valid oauthClientId + no secret → Thrift runs U2M, SEA throws AuthenticationError. The
   comment still claims it "mirrors thrift's DBSQLClient.createAuthProvider (DBSQLClient.ts:143)" — wrong line (:216) and wrong claim. And SEA's U2M arm hardcodes databricks-cli and rejects any client id, so
   this is a genuine capability gap, not just routing. → fix the comment and document the divergence + the U2M-no-custom-id limitation honestly.
2. Stale source line ref DBSQLOperation.ts:209 (carryover Setup E2E tests with GitHub Actions #2 from [SEA-NodeJS] (8/8) M1 Phase 1 — OAuth M2M + OAuth U2M (5 review rounds, ZERO HIGH at close) #383 — PERSISTS) — SeaErrorMapping.ts:54 and the :702-region comment. The actual errorCode === OperationStateErrorCode.Canceled switch is now
   at :374/:376; :209 is unrelated. The namespacing design is correct — only the ref drifted. → update or drop the line number.

🟡 P2 (Minor)

• SeaBackendOptions.context optional + blind as IClientContext (carryover Update CHANGELOG #3 — PERSISTS, unreachable today) — SeaBackend.ts:415 can store undefined; the only prod caller always passes {context: this}, and
  session methods throw before derefing it. Latent NPE when M1 wires executeStatement to use context. → make required + stub in tests, or guard.
• prependSlash not actually shared — the new lib/utils/prependSlash.ts docstring claims it's shared by DBSQLClient and SeaAuth "so the two can't drift," but neither imports it; both keep private copies (now
  3 identical impls). No correctness impact. → import it at both sites or drop the file.
• Cancelled/Timeout mapping discards the default state message — SeaErrorMapping.ts:626-635 overwrites the enum's canonical message with kernel text. Intentional; flagged only for consumers relying on the
  canonical message.

Thanks @gopalldb — validated all of these against the source; addressed in the latest push (f6418e0, plus the rebased stack). Summary:

🔴 P0 — packaging

• Garbled npm names: confirmed — the M0 triple was baked into the prefix for every platform (@databricks/sea-native-linux-x64-gnu-darwin-arm64, and the doubled …-gnu-linux-x64-gnu). Corrected the router to the canonical @databricks/sql-kernel-<triple> (matches the loader hint + native/sea/README.md). Added tests/unit/sea/native-packaging.test.ts asserting every @databricks/* require matches @databricks/sql-kernel-<triple> and that the garbled/doubled prefixes never reappear. (The root cause is the kernel's napi package.name; this fixes the committed/shipped router, and the kernel config needs the matching change so a future build:native doesn't regress it.)
• @napi-rs/cli in optionalDependencies: agreed — a build tool shouldn't land in consumer installs. Removed it from optionalDependencies; build:native now fetches it on demand via npx --yes @napi-rs/cli@2.18.4.
• Per-platform packages not declared: these aren't published yet, and npm ci hard-fails on a pinned dependency it can't resolve from the registry — so declaring them now would break every install. Left undeclared for M0; native/sea/README.md now documents that the binding comes from build:native locally until the packages publish (at which point they go back into optionalDependencies). Could not write the "require-name matches an optionalDependencies key" test for the same reason; the naming-regression test above is the M0 stand-in.

🟠 P1

1. M2M/U2M flow selection: confirmed the divergence and rewrote the docs honestly — Thrift keys off the secret (DBSQLClient.ts:216), SEA keys off oauthClientId presence, with both real gaps spelled out (id + no secret throws where Thrift runs U2M; SEA U2M has no custom client id). Fixed the wrong :143 ref and dropped the misleading "mirrors thrift" claim.
2. Stale DBSQLOperation.ts:209: updated to ~:374 (the actual errorCode === OperationStateErrorCode.Canceled switch) in both spots.

🟡 P2

• SeaBackendOptions.context: made required (removed the as IClientContext downcast of undefined) so a missing context is a compile error, not a latent NPE. Tests pass a shared makeFakeContext().
• prependSlash: dropped the dead lib/utils/prependSlash.ts — nothing imported it; SeaAuth and DBSQLClient each keep their own inline copy.
• Cancelled/Timeout canonical message: intentional, leaving as-is per your note.

None of these were already fixed downstream; the fixes live in #409 and propagate through the rebased #410/#411.

This pull request and its description were written by Isaac.