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jsonparser
ProbeLabsviewing a historical runThe fastest JSON parser for Go — formally verified with ReqProof (real library, master).
When ParseString encounters a UTF-16 high surrogate escape followed by a second unicode escape whose value is below the low surrogate range (e.g., '\uD800\u0041'), the parser shall substitute U+FFFD (replacement character) for the malformed surrogate sequence and continue parsing, matching encoding/json behavior, rather than producing corrupted output or returning an error.
Specification
The requirement exactly as authored — its complete prose text and, where present, the formal FRETish sentence it compiles to.
When ParseString encounters a UTF-16 high surrogate escape followed by a second unicode escape whose value is below the low surrogate range (e.g., '\uD800\u0041'), the parser shall substitute U+FFFD (replacement character) for the malformed surrogate sequence and continue parsing, matching encoding/json behavior, rather than producing corrupted output or returning an error.
the parser shall always satisfy !raw_string_has_invalid_low_surrogate | substitutes_replacement_for_invalid_low_surrogate
Rationale & tags
Why this requirement exists, and how it is categorised.
Rationale & tags
Why this requirement exists, and how it is categorised.
An invalid low surrogate (valid unicode escape but wrong range) exercises a different branch in decodeUnicodeEscape than a completely missing second escape.
Verification & provenance
How this requirement was checked: the review trail, edit history, and the machine-analysis status terms (each ⓘ explains what it means).
Review
- Status
- approved
- Reviewer
- Buger · lead_engineer
- Reviewed
- Jul 27, 2026, 11:43 UTC
History
- Created
- Apr 14, 2026, 18:00 UTC · Claude · AI agent
- Modified
- Jul 27, 2026, 11:43 UTC · Buger
Change history
Every recorded revision of this requirement's source file — newest first, each with its commit message and the diff for that change.
Every recorded revision of this object's source — newest first, each with the commit message and its file-level diff.
Obligations
What this requirement must witness to be considered satisfied — the required evidence, and the tests that discharge each one.
The tests that discharge each obligation aren't available for a historical run
The evidence matrix behind each obligation comes from the live audit index, which can't be rebuilt for a past commit. Nothing here means unknown — not that the requirement has no obligations.
Formula evidence
The formal formula behind this requirement, the variables it is written over, and the tests that exercise it (each term is explained inline).
Formula evidence
The formal formula behind this requirement, the variables it is written over, and the tests that exercise it (each term is explained inline).
FRETish formula
the parser shall always satisfy !raw_string_has_invalid_low_surrogate | substitutes_replacement_for_invalid_low_surrogate
Variables
| Name | Type | Direction | Description |
|---|---|---|---|
| raw_string_has_invalid_low_surrogate | — | True when ParseString encounters a UTF-16 high surrogate followed by a unicode escape whose value is below the low surrogate range. | |
| substitutes_replacement_for_invalid_low_surrogate | — | True when ParseString substitutes U+FFFD for a high surrogate followed by an invalid low surrogate, matching encoding/json behavior. |
Witnesses· 2 scenarios total
- TestMCDC_SYS_REQ_062_Row1_TriggerFalseexercises 1 condition scenario
- TestMCDC_SYS_REQ_062_Row3_InvalidLowSurrogateErrorexercises 1 condition scenario
MC/DC truth table· 3 rows
Each row assigns the formula's conditions (T/F) and shows the Result— the formula's value for that input row, not a test pass/fail. A row proves a condition when flipping only that condition flips the outcome. The test that covers each row is linked.
mcdc:ignoreNo-actionfalse-result row satisfied by designUncoveredneeds a covering test| # | raw_string_has_invalid_low_surrogate | substitutes_replacement_for_invalid_low_surrogate | Result | Proves | Covering test |
|---|---|---|---|---|---|
| 1 | F | F | T | raw_string_has_invalid_low_surrogate | |
| 2 | T | F | F | raw_string_has_invalid_low_surrogate | Exempted · defensive — Unreachable in the correct build: the escape.go fix (DEFECT-260727-SNGT) always substitutes U+FFFD for a high surrogate followed by an invalid low surrogate, so when raw_string_has_invalid_low_surrogate=T the substitutes_replacement_for_invalid_low_surrogate output is always T (witnessed by Row 3 below). The (T,F) violation row can only occur in the pre-fix build that returned an error. Positive path Row 1 (F,F) and the substitution-when-triggered Row 3 (T,T) are both witnessed. (reviewed: human:buger) |
| 3 | T | T | T | substitutes_replacement_for_invalid_low_surrogate |
Its place
This requirement inside its trace neighbourhood — authored trace links only; automatically derived links come from the audit index and aren't shown here.
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Trace evidence
The concrete artifacts linked to this requirement — implementing code, verifying tests, documents, and the findings raised against it.
No findings affect this requirement
Nothing was flagged against this requirement in the pinned run.
Impact
Blast radius — authored trace links only (automatically derived links come from the audit index and aren't shown here).
Impact
Blast radius — authored trace links only (automatically derived links come from the audit index and aren't shown here).
If you change this
Tests to re-run (2)
- deep_spec_test.godeep_spec_test.go
- mcdc_spec_witnesses_test.gomcdc_spec_witnesses_test.go
What this rests on
Parent requirements (1)
Discussions
Discuss this with the proof team. Nothing changes in your audit automatically — you open a request and a staff member records any outcome inside the thread.