debugger: preserve overlapping CDP request state

[trivikr]

A breakpoint pause can arrive before the preceding Debugger.resume
request has finished. When that happens, the probe evaluation becomes the
current inFlight request, but the older resume request clears it when it
finishes.

If the target exits during the probe evaluation, we then lose the
information needed to attribute the failure to that probe. This caused the
test to intermittently report the probe as still pending, most notably on
Windows CI.

This change makes each request clear inFlight only when it still owns
that state. It also adds a deterministic regression test that reproduces
the ordering without relying on inspector timing.

Refs: https://github.com/nodejs/reliability/issues?q=sort%3Aupdated-desc%20test-debugger-probe-failure-process-exit

Example Error

  ---
  duration_ms: 2673.03700
  severity: fail
  exitcode: 1
  stack: |-
    [process 13216]: --- stderr ---
    INSPECT_PROBE 13216: child stderr: "Debugger listening on ws://127.0.0.1:51299/8810a2af-54fc-49c1-9dd9-888d0b156452\r\nFor help, see: https://nodejs.org/learn/getting-started/debugging\r\n"
    INSPECT_PROBE 13216: CDP -> Runtime.enable
    INSPECT_PROBE 13216: child stderr: "Debugger attached.\r\n"
    INSPECT_PROBE 13216: CDP <- Runtime.enable (success)
    INSPECT_PROBE 13216: CDP -> Debugger.enable
    INSPECT_PROBE 13216: CDP <- Debugger.enable (success)
    INSPECT_PROBE 13216: CDP -> Debugger.setBreakpointByUrl
    INSPECT_PROBE 13216: CDP <- Debugger.setBreakpointByUrl (success)
    INSPECT_PROBE 13216: breakpoint set: id=2:7:0:^(.*[\/\\])?probe-exits-during-probe\.js$ urlRegex=^(.*[\/\\])?probe-exits-during-probe\.js$ locations=[]
    INSPECT_PROBE 13216: CDP -> Runtime.runIfWaitingForDebugger
    INSPECT_PROBE 13216: CDP <- Runtime.runIfWaitingForDebugger (success)
    INSPECT_PROBE 13216: scriptParsed: scriptId=89 url=evalmachine.<anonymous>, length=4
    INSPECT_PROBE 13216: scriptParsed: scriptId=90 url=file:///c:/workspace/node-test-binary-windows-js-suites/node/test/fixtures/debugger/probe-exits-during-probe.js, length=138
    INSPECT_PROBE 13216: paused: finished=0, reason=Break on start hitBreakpoints=[]
    INSPECT_PROBE 13216: CDP -> Debugger.resume
    INSPECT_PROBE 13216: paused: finished=0, reason=other hitBreakpoints=["2:7:0:^(.*[\\/\\\\])?probe-exits-during-probe\\.js$"]
    INSPECT_PROBE 13216: CDP -> Debugger.evaluateOnCallFrame, probe=0
    INSPECT_PROBE 13216: CDP <- Debugger.resume (success)
    INSPECT_PROBE 13216: child stderr: "Waiting for the debugger to disconnect...\r\n"
    INSPECT_PROBE 13216: disconnect sentinel detected, resetting client
    INSPECT_PROBE 13216: CDP <- Debugger.evaluateOnCallFrame error: ERR_DEBUGGER_ERROR
    INSPECT_PROBE 13216: recordInspectorFailure "Target process exited during probe evaluation": inFlight=null, lastProbeIndex=null, cdpError=undefined
    INSPECT_PROBE 13216: finish: exitCode=1, terminal=error
    
    [process 13216]: --- stdout ---
    {"v":2,"probes":[{"expr":"exitDuringProbe()","target":{"suffix":"probe-exits-during-probe.js","line":8}}],"results":[{"event":"error","pending":[0],"error":{"code":"probe_failure","message":"Target process exited during probe evaluation before probes: probe-exits-during-probe.js:8. If the failure repeats, review the probe expression.","stderr":""}}]}
    
    [process 13216]: status = 1, signal = null
    c:\workspace\node-test-binary-windows-js-suites\node\test\common\child_process.js:112
        throw error;
        ^
    
    Error: - stdout did not match expectation, checker throws:
    AssertionError [ERR_ASSERTION]: Expected values to be strictly deep-equal:
    + actual - expected
    ... Skipped lines
    
      {
        probes: [
          {
            expr: 'exitDuringProbe()',
            target: {
    ...
            error: {
    -         message: 'Probe evaluation did not complete'
    -       },
    -       event: 'hit',
    -       hit: 1,
    -       location: {
    -         column: 1,
    -         line: 8,
    -         url: 'file:///c:/workspace/node-test-binary-windows-js-suites/node/test/fixtures/debugger/probe-exits-during-probe.js'
    -       },
    -       probe: 0
    -     },
    -     {
    -       error: {
              code: 'probe_failure',
    +         message: 'Target process exited during probe evaluation before probes: probe-exits-during-probe.js:8. If the failure repeats, review the probe expression.',
    -         details: {
    -           lastCdpMethod: 'Debugger.evaluateOnCallFrame'
    -         },
    -         message: 'Target process exited during probe evaluation. If the failure repeats, review the probe expression.',
    -         probe: 0,
              stderr: ''
            },
            event: 'error',
    +       pending: [
    +         0
    +       ]
    -       pending: []
          }
        ],
        v: 2
      }
    
        at assertProbeJson (c:\workspace\node-test-binary-windows-js-suites\node\test\common\debugger-probe.js:65:10)
        at stdout (c:\workspace\node-test-binary-windows-js-suites\node\test\parallel\test-debugger-probe-failure-process-exit.js:25:5)
        at checkOutput (c:\workspace\node-test-binary-windows-js-suites\node\test\common\child_process.js:52:7)
        at expectSyncExit (c:\workspace\node-test-binary-windows-js-suites\node\test\common\child_process.js:129:32)
        at spawnSyncAndExit (c:\workspace\node-test-binary-windows-js-suites\node\test\common\child_process.js:143:10)
        at Object.<anonymous> (c:\workspace\node-test-binary-windows-js-suites\node\test\parallel\test-debugger-probe-failure-process-exit.js:17:1)
        at Module._compile (node:internal/modules/cjs/loader:1937:14)
        at Object..js (node:internal/modules/cjs/loader:2077:10)
        at Module.load (node:internal/modules/cjs/loader:1659:32)
        at Module._load (node:internal/modules/cjs/loader:1451:12) {
      generatedMessage: true,
      code: 'ERR_ASSERTION',
      actual: [Object],
      expected: [Object],
      operator: 'deepStrictEqual',
      diff: 'simple'
    }
        at Object.<anonymous> (c:\workspace\node-test-binary-windows-js-suites\node\test\parallel\test-debugger-probe-failure-process-exit.js:17:1)
        at Module._compile (node:internal/modules/cjs/loader:1937:14)
        at Object..js (node:internal/modules/cjs/loader:2077:10)
        at Module.load (node:internal/modules/cjs/loader:1659:32)
        at Module._load (node:internal/modules/cjs/loader:1451:12)
        at wrapModuleLoad (node:internal/modules/cjs/loader:261:19)
        at Module.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:154:5)
        at node:internal/main/run_main_module:33:47 {
      options: {
        cwd: 'c:\\workspace\\node-test-binary-windows-js-suites\\node\\test\\fixtures\\debugger',
        env: { NODE_DEBUG: 'inspect_probe' }
      },
      command: 'c:\\workspace\\node-test-binary-windows-js-suites\\node\\Release\\node.exe inspect --json --probe probe-exits-during-probe.js:8 --expr exitDuringProbe() probe-exits-during-probe.js'
    }

---

Assisted-by: openai:gpt-5.6-sol

[trivikr]

The stress test isn't runnable on Windows environments mentioned in reports, as clang is not available

Discussion on Slack: https://openjs-foundation.slack.com/archives/C03BJP63CH0/p1783477923723679

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.24%. Comparing base (b4c7be3) to head (7d883b8).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #64467      +/-   ##
==========================================
+ Coverage   90.23%   90.24%   +0.01%     
==========================================
  Files         741      741              
  Lines      241604   241607       +3     
  Branches    45520    45522       +2     
==========================================
+ Hits       218010   218042      +32     
+ Misses      15120    15114       -6     
+ Partials     8474     8451      -23     

Files with missing lines	Coverage Δ
lib/internal/debugger/inspect_probe.js	81.09% <100.00%> (+0.05%)	⬆️

... and 25 files with indirect coverage changes

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[mcollina]

lgtm