test(task): add contract tests for repair-args double-encode detection

[oldschoola]

Summary

Adds 17 contract tests for repairDoubleEncodedJsonString and repairTaskParams in packages/coding-agent/src/task/repair-args.ts — a pure function module with no prior test coverage.

What's tested

repairDoubleEncodedJsonString (9 tests)

• Repairs double-encoded newlines, quotes, and unicode (the core contract)
• Leaves normal prose untouched (fast path)
• Leaves strings with no backslash untouched
• Leaves a lone \n mention untouched (incidental, not double-encoded — hasDoubleEncodeSignature requires a structural escape or 2+ backslashes)
• Repairs strings with structural escapes (```)
• Repairs strings with backslash-backslash (\\)
• Leaves Windows paths with single backslash untouched (\U is not a valid JSON escape)
• Leaves regex patterns untouched (\d is not a valid JSON escape)
• Returns same reference when nothing changed

repairTaskParams (8 tests)

• Repairs double-encoded assignment in flat form
• Repairs double-encoded description in flat form
• Repairs double-encoded context in batch form
• Repairs double-encoded fields in batch task items
• Returns same reference when nothing needs repair
• Handles null/undefined params defensively
• Handles params with undefined optional fields
• Handles partially streamed params (missing fields)

Verification

• bun check passes
• 17 tests pass, 0 fail

[roboomp]

review:p0 for a small test-only change with no production behavior risk; targeted repair tests pass locally (27 pass, including the existing suite).
Two should-fix cleanup items: the new file duplicates existing repair-args coverage on origin/main, and one string “same reference” assertion is tautological for a primitive.
Thanks for tightening coverage around the task argument repair path.

[roboomp]

should-fix: origin/main already has packages/coding-agent/test/tools/task-repair-args.test.ts covering the same repairDoubleEncodedJsonString contract (uniform decode, Windows paths, regexes, lone \n, no-op). Adding a second suite here duplicates those cases and splits the contract across two files; please fold only the new batch/context/defensive cases into the existing test file, or move the existing suite rather than keeping both.

[roboomp]

should-fix: string is a primitive, so toBe(input) here checks value equality, not object identity/reference reuse. This duplicates the no-backslash no-op assertions above without defending a separate contract; either drop it or change the test to an object-level identity case like repairTaskParams already does.

[oldschoola]

Fixed in the latest push. Removed the duplicate packages/coding-agent/test/task/repair-args.test.ts and folded only the new cases (backslash-backslash decode, batch form context repair, per-task-item repair, null/undefined defensive handling, partially streamed params) into the existing packages/coding-agent/test/tools/task-repair-args.test.ts. Also removed the toBe(input) reference-stability assertion on a string primitive (the existing repairTaskParams test already covers object-level identity).

[oldschoola]

Closing — the reviewer correctly identified that packages/coding-agent/test/tools/task-repair-args.test.ts already exists on origin/main and covers the same repairDoubleEncodedJsonString contract (uniform decode, Windows paths, regexes). This PR duplicates existing coverage without adding new contracts. The second review point about toBe(input) testing value equality rather than reference identity for primitives is also valid — the assertion doesn't defend a distinct contract.