PATCHVERDICT.Candidate repairs. Recorded evidence.
New mission VERIFIED
Mission controlweb-4ac3cf2d-4bdd-4c96-b73b-dabca9c82109
Proof bundle

PATCH VERIFICATION MISSION

range includes the end boundary

Bug description

The range utility returns one extra value at the end of the generated sequence. It should include values from the start up to, but not including, the end boundary while preserving normal range behavior.

Reproduction

Run:

npm test
Repositoryhttps://github.com/prahans/patchverdict-off-by-one.git
Issue#1 · View original issue
Execution status
COMPLETED
Base commit
e2fc49af003df0234fdeb126fcb5b84eae5a532b
Changed files
1file
Investigation
6iterations
MISSION RECORDREASONING / EVIDENCE / VERDICT

Flight Recorder

15 events / UTC
  1. BASELINERunning reproduction test before patch
  2. BASELINEReported bug reproduced
  3. INVESTIGATINGAI investigation started
  4. INVESTIGATINGAI investigation completed
  5. PATCHINGAI patch phase started
  6. PATCHINGCandidate patch applied
  7. PATCHINGGit captured 1 changed file(s)
  8. PATCHINGGit diff captured
  9. PATCHINGVerification integrity preserved
  10. VERIFYINGRunning reproduction test after patch
  11. VERIFYINGReproduction test passes after patch
  12. VERIFYINGRunning full test suite
  13. VERIFYINGFull test suite passes
  14. VERDICTCalculating deterministic verdict
  15. COMPLETEDMission completed with verdict VERIFIED
Recorded execution eventsSAVED EVENTS

Proof Chain

RECORDED CHECKS
Evidence requirements6 passed
  1. Configured failure reproducedPassed · Baseline · exit 1
    01
  2. Candidate patch appliedPassed · 1 file changed
    02
  3. Git diff capturedPassed · Against e2fc49a
    03
  4. Integrity checksPassed · No recognized integrity concerns detected
    04
  5. Reproduction passes after patchPassed · Configured reproduction · exit 0
    05
  6. Repository test script passesPassed · Repository tests · exit 0
    06
REPAIR VERDICTVERIFIED
RECORDED VERDICT

Repair verdicts apply to the recorded requirements and execution.
Integrity checks detect recognized risks; they do not guarantee correctness.

Git evidence

Candidate patch

The candidate change captured from the sandbox working tree.

src/range.js
+1−1
diff --git a/src/range.js b/src/range.js
index 2eac330..e3ebcf2 100644
--- a/src/range.js
+++ b/src/range.js
@@ -1,7 +1,7 @@
11 export function range(start, end) {
22 const values = [];
33
4− for (let value = start; value <= end; value++) {
4+ for (let value = start; value < end; value++) {
55 values.push(value);
66 }
1 file changedBase e2fc49a

AI investigation report

AI REASONING

PROPOSED DIAGNOSIS

Investigation Report

Inspected src/range.js and src/range.test.js. The implementation uses value <= end in the loop condition, causing the end boundary to be included in the result. All three tests fail because the expected behavior is a half-open interval [start, end) where end is excluded. The root cause is clearly identified: the loop condition should use < instead of <=.

Patch target
src/range.js
Test file
src/range.test.js
Reproduction command
npm test
6 investigation iterationsReasoning, not proof
Execution evidence

Verification evidence

Recorded command results. Expand a run to inspect its output.

Baseline reproduction

npm test
1.33sexit 1FAILURE REPRODUCED

stdout


> patchverdict-off-by-one@1.0.0 test
> vitest run


 RUN  v3.2.4 /tmp/patchverdict

 ❯ src/range.test.js (3 tests | 3 failed) 15ms
   × range > includes the start and excludes the end 11ms
     → expected [ 1, 2, 3, 4 ] to deeply equal [ 1, 2, 3 ]
   × range > returns an empty array when start equals end 2ms
     → expected [ 5 ] to deeply equal []
   × range > supports negative values 1ms
     → expected [ -2, -1, +0, 1 ] to deeply equal [ -2, -1, +0 ]

 Test Files  1 failed (1)
      Tests  3 failed (3)
   Start at  10:06:16
   Duration  322ms (transform 52ms, setup 0ms, collect 36ms, tests 15ms, environment 0ms, prepare 119ms)

stderr


⎯⎯⎯⎯⎯⎯⎯ Failed Tests 3 ⎯⎯⎯⎯⎯⎯⎯

 FAIL  src/range.test.js > range > includes the start and excludes the end
AssertionError: expected [ 1, 2, 3, 4 ] to deeply equal [ 1, 2, 3 ]

- Expected
+ Received

  [
    1,
    2,
    3,
+   4,
  ]

 ❯ src/range.test.js:6:25
      4| describe("range", () => {
      5|   it("includes the start and excludes the end", () => {
      6|     expect(range(1, 4)).toEqual([1, 2, 3]);
       |                         ^
      7|   });
      8| 

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯[1/3]⎯

 FAIL  src/range.test.js > range > returns an empty array when start equals end
AssertionError: expected [ 5 ] to deeply equal []

- Expected
+ Received

- []
+ [
+   5,
+ ]

 ❯ src/range.test.js:10:25
      8| 
      9|   it("returns an empty array when start equals end", () => {
     10|     expect(range(5, 5)).toEqual([]);
       |                         ^
     11|   });
     12| 

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯[2/3]⎯

 FAIL  src/range.test.js > range > supports negative values
AssertionError: expected [ -2, -1, +0, 1 ] to deeply equal [ -2, -1, +0 ]

- Expected
+ Received

  [
    -2,
    -1,
    0,
+   1,
  ]

 ❯ src/range.test.js:14:26
     12| 
     13|   it("supports negative values", () => {
     14|     expect(range(-2, 1)).toEqual([-2, -1, 0]);
       |                          ^
     15|   });
     16| });

⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯⎯[3/3]⎯

Post-patch reproduction

npm test
2.13sexit 0PASS

stdout


> patchverdict-off-by-one@1.0.0 test
> vitest run


 RUN  v3.2.4 /tmp/patchverdict

 ✓ src/range.test.js (3 tests) 3ms

 Test Files  1 passed (1)
      Tests  3 passed (3)
   Start at  10:06:45
   Duration  323ms (transform 50ms, setup 0ms, collect 29ms, tests 3ms, environment 0ms, prepare 98ms)

stderr

(no output)

Repository test script

npm test
1.29sexit 0PASS

stdout


> patchverdict-off-by-one@1.0.0 test
> vitest run


 RUN  v3.2.4 /tmp/patchverdict

 ✓ src/range.test.js (3 tests) 3ms

 Test Files  1 passed (1)
      Tests  3 passed (3)
   Start at  10:06:46
   Duration  277ms (transform 45ms, setup 0ms, collect 27ms, tests 3ms, environment 0ms, prepare 100ms)

stderr

(no output)

Baseline labels reflect the configured failure expectation. Post-patch success uses exit code zero; the verdict also depends on patch and integrity checks.