[Blind-Striker]

📝 Description

What does this PR do?
It is TST-E4a's first PR. It adds the declared-error door table that later PRs will convert about a hundred per-door test methods into, and converts one pilot row so the mechanism can be reviewed before any batch conversion.

• Common/Errors/DeclaredErrorTests, with its two row records in the slice's own Common/Support/ (testing-style.md: a one-slice helper lives in its slice's Support/), runs one row source on two spines:

  • throwing: Throws<OpenCodeApiException>, the exact status and the exact error type;
  • NoThrow: IsError, the exact status and the exact error type.

  A row is one door, one canned error and one expectation. The spine is the test method, so a row's data is never written twice.

• The rows' expectations come from the pinned spec, not from generated code. A third test, Every_Row_Should_Match_The_Pinned_Declaration, resolves each row's JSON pointer in spec/openapi.json. It checks that:

  • the operationId sits at the row's method and path;
  • the pointer belongs to that operation's response for the row's status;
  • the referenced component's _tag is the row's tag.

  The spec is linked into the test assembly as an embedded resource (Fixtures/Pinned/openapi.json) and read through the existing FixtureLoader, so it reaches every OS leg and net472. The guard is one-way: it proves each row against the pin, and does not try to find every declared error.

• The pilot row, worktree.create:400:InvalidRequestError, replaces WorktreesClientContractTests.CreateWorktreeAsync_Should_Throw_The_Other_Declared_400_Error. It keeps the same door, the same request (ProjectId "prj_1", Directory "/repo/feature") and the same canned BadRequest with WireBodyData.InvalidRequestError, and it now also runs on the NoThrow spine.

• The row names its SDK member with nameof(WorktreesClient.CreateWorktreeAsync), so a renamed member breaks the build instead of leaving a stale string. The member is shown in the test's display name.

Two shape choices worth knowing:

• DeclaredErrorCase is a readonly record struct. The test class and its records are public, matching every other test class. A public test method that dereferences a reference-type parameter trips CA1062, which this repository sets to error; a value-type row avoids that without a null check in every test.
• The comment above GetString()! stays, on purpose. It states the guarantee behind the ! (SLOP-08).

One status field. At the base, every one of the 106 declared-error methods that the later PRs will convert answers with the same status it asserts, so the row has a single Status, used for both the canned response and the expectation. The wrong-status mutant below shows that a single field still guards it.

🔄 Type of Change

• 🧪 Test improvements

🎯 Protocol & API Surface

• No change to the public API surface
• Nothing under external/, spec/ or src/ was touched (the spec is only linked into the test project)

🧪 Testing

Test mapping (mechanical: e4_test_map.py over git diff 3b235436 850477cd)

File	Base test method	At head	Target
tests/OpenCode.Sdk.Tests/Worktrees/WorktreesClientContractTests.cs	CreateWorktreeAsync_Should_Throw_The_Other_Declared_400_Error	row	worktree.create:400:InvalidRequestError

Unmapped: 0

File	Assert.That at base	at head	delta
tests/OpenCode.Sdk.Tests/Common/Errors/DeclaredErrorTests.cs	0	12	+12
tests/OpenCode.Sdk.Tests/Common/Support/DeclaredErrorCase.cs	0	0	+0
tests/OpenCode.Sdk.Tests/Common/Support/DeclaredErrorDoor.cs	0	0	+0
tests/OpenCode.Sdk.Tests/Worktrees/WorktreesClientContractTests.cs	68	65	-3

The WorktreesClientContractTests delta is the deleted method's three assertions. The row asserts the status and the exact type on both spines; the deleted method asserted them on the throwing spine only.

Mutants (net10.0, analyzers on, each restored byte-identically)

Mutant	Killed by
Equivalence: WorktreeCreateResponseAdapter Status400Tags without InvalidRequestError	base: the deleted method red (UnknownOpenCodeError); head: the row red on both spines
Wrong status (the single field BadRequest → Unauthorized)	both spines and the guard
Wrong error type	both spines
Pointer to the 401 response; to anyOf/0 (WorktreeError); to another operation; a pointer that does not resolve; a wrong operationId; a wrong tag	the guard

Evidence

• Dispatch harness on the worker's commit: build, Sdk.Tests net10.0 2797/0 and net472 2802/0, Tools.Tests 2019/0, verify-clones 0 new, slopwatch clean.
• After the coordinator's fix-up: the focused classes pass 22/0 on net10.0 and net472. The fix-up added the nameof, the single status field, public visibility, and the stated-guarantee comment.
• Review: the coordinator read the diff, and a second-family reviewer (Grok, given only the requirements and the diff) reviewed it. Grok's one defect: MemberName was never read, so a door labelled with the wrong member would still pass. It is resolved in part: the name is now a compile-checked nameof and part of the display name. A label naming a different, existing member would still pass, because a lambda cannot tell the test which member it calls. Grok's placement note (move the records from the root Support/ to the slice) is applied. Its comment note agrees that the comment is the !'s stated guarantee.

✅ Completion Gate

Local check (quality-gates.md) on fcbbaa6f, base 3b235436. Every step's own exit code was read. The final head 850477cd only moves the two record files into Common/Support/ and changes their namespace. On it: the full build has 0 warnings and 0 errors; the focused classes pass 22/0 on net10.0 and net472; the whole Tools.Tests project passes 2033/0; format, slopwatch and verify-clones are clean.

• slopwatch: zero findings
• dotnet build --configuration Release: 0 warnings, 0 errors
• dotnet format whitespace / dotnet format style --severity warn: no changes
• verify-clones: passed, 0 new (tests 5.42%); baseline −2 entries only
• OpenCode.Sdk.Tools.Tests (all but NativeAot): 2033, 0 failed
• OpenCode.Sdk.Tests (all but ServiceElection/NativeAot): 8396, 0 failed

The host runs Bun 1.4.3, a maintainer-named off-pin host (OPENCODE_SDK_TESTS_BUN_MISMATCH=allow); the pin is 1.4.2.

✅ Code Quality Checklist

• No new suppression
• No tests skipped or weakened; the one removed method is mapped to its row above

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