Fix KaStringAsync.KeyEquals branch-1 offset arithmetic for non-prefix Contains matches

QuickFiler.Test/Controllers/KaStringAsyncTests.cs

@@ -89,13 +89,44 @@ public void KeyEquals_ContainsMatchWhileActivated_InvokesUpdateAndReturnsTrue()
             result.Should().BeTrue("a substring match returns true");
             updateArg
                 .Should()
-                .Be("b", "Update receives Key.Substring(other.Length - 1, 1) => index 1 => \"b\"");
+                .Be(
+                    "b",
+                    "Update receives the last character of the matched span (Key.IndexOf(\"ab\", StringComparison.Ordinal) + other.Length - 1 = 1) => \"b\""
+                );
             ka.Activated.Should()
                 .BeTrue(
                     "the contains-match branch returns before the trailing Activated = false reset"
                 );
         }
 
+        [TestMethod]
+        public void KeyEquals_ContainsMatchAtNonPrefixIndex_InvokesUpdateWithLastMatchedCharacter()
+        {
+            // Intent: issue #583 regression. Branch 1's Update argument was computed as
+            // Key.Substring(other.Length - 1, 1), which is only correct when other is a prefix
+            // of Key. For Key="01" and other="1", the probe matches at index 1, not index 0.
+            // Before the fix this yielded "0"; after the fix it yields "1".
+
+            // Arrange
+            string updateArg = null;
+            var ka = NewKa("01", update: s => updateArg = s);
+            ka.Activated = true;
+
+            // Act
+            var result = ka.KeyEquals("1");
+
+            // Assert
+            result.Should().BeTrue("a substring match returns true");
+            updateArg
+                .Should()
+                .Be(
+                    "1",
+                    "Update receives the last character of the matched span (Key.IndexOf(\"1\", "
+                        + "StringComparison.Ordinal) + other.Length - 1 = 1), not the pre-fix "
+                        + "prefix-only offset that yielded \"0\""
+                );
+        }
+
         [TestMethod]
         public void KeyEquals_ContainsMatchWhileNotActivated_ReturnsTrueWithoutUpdate()
         {

QuickFiler/Controllers/KaStringAsync.cs

@@ -78,8 +78,10 @@ public bool Activated
         /// </para>
         /// <para>
         /// <b>Argument contract.</b> <paramref name="other"/> must be non-null and non-empty. The
-        /// guard clause at the top of this method rejects both fail-fast, so branch 1's substring
-        /// offset expression is never evaluated with a negative start index.
+        /// guard clause at the top of this method rejects both fail-fast, so branch 1's derived
+        /// offset (Key.IndexOf(other) plus the matched length) is never evaluated with a
+        /// negative start index: IndexOf is non-negative because branch 1 only runs when
+        /// Contains already matched, and other.Length is at least 1 because of the guard above.
         /// </para>
         /// <para>
         /// <b>Consequence for callers.</b> <c>KbdActions</c> methods whose key type is
@@ -125,7 +127,12 @@ public bool KeyEquals(string other)
             if (Key.Contains(other))
             {
                 if (Activated && Update is not null)
-                    Update(Key.Substring(other.Length - 1, 1));
+                    Update(
+                        Key.Substring(
+                            Key.IndexOf(other, StringComparison.Ordinal) + other.Length - 1,
+                            1
+                        )
+                    );
                 return true;
             }
             else if (other.Length == 1)

docs/features/active/kastringasync-keyequals-contains-offset-583/evidence/baseline/coverage-baseline.md

@@ -0,0 +1,135 @@
+# Coverage Baseline (P0-T8)
+
+- Timestamp: 2026-09-13T01-00
+- Command: <resolved dotnet-coverage executable> collect --output <session-temp-file>
+  --output-format cobertura --settings <dotnet-coverage module-exclude settings file> --
+  <resolved vstest executable> QuickFiler.Test\bin\Debug\QuickFiler.Test.dll /InIsolation
+  /Settings:scripts\vscode\TaskMaster.cli.runsettings
+  "/TestCaseFilter:TestCategory!=LiveOutlook"
+- EXIT_CODE: 0
+
+## Deviation note — dotnet-coverage module-exclude settings
+
+The first attempt at this capture, using only the TaskMaster CLI runsettings file with no
+dotnet-coverage module excludes, failed 3 of 1393 tests
+(InitEmailQueue_ZeroBatchSize_ReturnsEmptyListWithoutThrowing,
+InitEmailQueue_ZeroBatchSize_StillStartsBackgroundWorker,
+InitEmailQueue_PositiveBatchSize_RetainsExistingProjectionAndFrameDrop) with a
+System.TypeInitializationException on Deedle.Reflection / netstandard, Version=2.1.0.0. This is
+a known, pre-existing, environment-level failure mode of dotnet-coverage's own instrumentation
+against Deedle/F# assemblies, unrelated to KaStringAsync and unrelated to this branch's diff
+(confirmed no source diff from origin/main at the time of this capture). The repository's own
+TaskMaster.runsettings already carries a matching Deedle/FSharp module-exclude block for the
+built-in Code Coverage collector; dotnet-coverage's own instrumentation does not read that file,
+so an equivalent exclude was supplied to dotnet-coverage collect via its own --settings file
+(ModulePaths/Exclude for .*Deedle.*, .*FSharp.*, .*Castle\.Core.*, .*FluentAssertions.*,
+.*Moq.*, .*Microsoft\.Testing.*, .*MSTest.*), written to a temp-directory file, never added to
+the repository. With that settings file supplied, the same capture reported "Test Run
+Successful.", 1393/1393 Passed.
+
+## Test run result
+
+```
+Test Run Successful.
+Total tests: 1393
+     Passed: 1393
+ Total time: 15.6062 Seconds
+```
+
+## Root coverage figures
+
+- Root line-rate: 0.4298999577286177
+- Root branch-rate: 0.24095967959333
+
+## KaStringAsync.cs covered/total
+
+- Covered: 60
+- Total: 60
+
+## Per-line hits projection
+
+| Line | Hits |
+|---|---|
+| 12 | 1 |
+| 14 | 1 |
+| 15 | 1 |
+| 16 | 1 |
+| 17 | 1 |
+| 18 | 1 |
+| 19 | 1 |
+| 20 | 1 |
+| 21 | 1 |
+| 22 | 1 |
+| 23 | 1 |
+| 24 | 1 |
+| 25 | 1 |
+| 26 | 1 |
+| 27 | 1 |
+| 32 | 1 |
+| 33 | 1 |
+| 39 | 1 |
+| 40 | 1 |
+| 46 | 1 |
+| 47 | 1 |
+| 50 | 1 |
+| 53 | 1 |
+| 54 | 1 |
+| 107 | 1 |
+| 110 | 1 |
+| 111 | 1 |
+| 112 | 1 |
+| 115 | 1 |
+| 116 | 1 |
+| 117 | 1 |
+| 118 | 1 |
+| 119 | 1 |
+| 120 | 1 |
+| 121 | 1 |
+| 122 | 1 |
+| 125 | 1 |
+| 126 | 1 |
+| 127 | 1 |
+| 128 | 1 |
+| 129 | 1 |
+| 131 | 1 |
+| 132 | 1 |
+| 133 | 1 |
+| 134 | 1 |
+| 135 | 1 |
+| 136 | 1 |
+| 137 | 1 |
+| 138 | 1 |
+| 139 | 1 |
+| 140 | 1 |
+| 141 | 1 |
+| 142 | 1 |
+| 143 | 1 |
+| 144 | 1 |
+| 145 | 1 |
+| 150 | 1 |
+| 151 | 1 |
+| 157 | 1 |
+| 158 | 1 |
+
+## Raw output disposition
+
+- Raw-output location (relative to the per-user temp directory root): p583-p0t8b/coverage.cobertura.xml
+- Prefix comparison (raw-output full path begins with repository root full path): False
+- Post-deletion existence check of the raw file: False (absent)
+- Directory listing of evidence/baseline/ after deletion (entry names only):
+  - coverage-tool-probe.md
+  - csharpier-check.md
+  - dotnet-bootstrap.md
+  - msbuild-analyzers.md
+  - msbuild-nullable.md
+  - nuget-restore.md
+  - phase0-instructions-read.md
+
+## Output Summary
+
+Exit code 0; inner test run "Test Run Successful." with 0 Failed (1393/1393 Passed, after
+supplying a dotnet-coverage module-exclude settings file to work around a known pre-existing
+Deedle/FSharp instrumentation crash unrelated to this change); root line-rate
+0.4298999577286177, root branch-rate 0.24095967959333; KaStringAsync.cs covered/total 60/60;
+per-line hits projection holds 60 rows, no repeated line number; raw output confirmed outside
+the repository root and deleted; evidence/baseline/ directory listing contains no .xml entry.

docs/features/active/kastringasync-keyequals-contains-offset-583/evidence/baseline/coverage-tool-probe.md

@@ -0,0 +1,17 @@
+# Coverage Tool Probe
+
+- Timestamp: 2026-09-13T00-15
+- Command: Get-Command dotnet-coverage(.exe), then its version switch
+- EXIT_CODE: 0
+
+## Result
+
+- Present: yes (already installed as a global dotnet tool; no install step was needed)
+- Resolved path: <user-profile>\.dotnet\tools\dotnet-coverage.exe
+- Version string: 18.10.0+f4cc39224845ffa74bf246c9da2399d50e5d6342
+
+## Output Summary
+
+dotnet-coverage is present as a global tool, resolved path recorded above, version string
+18.10.0, observed exit code 0 for the version-switch invocation, matching the recorded shape at
+docs/features/archive/2026-08-07-quickfiler-keyboard-action-contract-defects-445/evidence/baseline/coverage-tool-probe.2026-08-22T09-32.md.

docs/features/active/kastringasync-keyequals-contains-offset-583/evidence/baseline/csharpier-check.md

@@ -0,0 +1,20 @@
+# CSharpier Check (Baseline)
+
+- Timestamp: 2026-09-13T00-20
+- Command: <resolved dotnet executable> tool run csharpier check . (run from repository root,
+  read-only)
+- EXIT_CODE: 0
+
+## Verbatim output
+
+```
+Checked 1624 files in 5999ms.
+```
+
+## Output Summary
+
+Files-checked count: 1624. Files-needing-formatting count: 0 (no per-file line appeared ahead
+of the summary line). Exit code 0, matching the recorded clean-tree shape ("Checked 1517 files
+in 6621ms.", exit code 0) at
+docs/features/archive/2026-08-07-quickfiler-keyboard-action-contract-defects-445/evidence/baseline/csharpier-check.2026-08-22T09-19.md;
+the higher file count here reflects the larger repository tree at this later point in time.

docs/features/active/kastringasync-keyequals-contains-offset-583/evidence/baseline/dotnet-bootstrap.md

@@ -0,0 +1,31 @@
+# Dotnet Bootstrap
+
+- Timestamp: 2026-09-13T00-05
+
+## Step 1 — SDK resolution
+
+The per-worktree .dotnet-sdk junction did not resolve (Test-Path returned False before this
+task ran). Fallback provisioner scripts/vscode/Install-RepoDotNetSdk.ps1 was run.
+
+- Command: pwsh -NoProfile -File scripts/vscode/Install-RepoDotNetSdk.ps1
+- Output: "Downloading .NET SDK 8.0.205 from
+  https://builds.dotnet.microsoft.com/dotnet/Sdk/8.0.205/dotnet-sdk-8.0.205-win-x64.zip...",
+  "Installed repo-local .NET SDK 8.0.205 to
+  <repo-root>\.dotnet-sdk."
+- Resolved dotnet executable: .dotnet-sdk/dotnet.exe (repo-relative), version switch confirms
+  8.0.205.
+- EXIT_CODE: 0
+
+## Step 2 — Tool restore
+
+- Command: <resolved dotnet executable> tool restore (run from repository root)
+- EXIT_CODE: 0
+- Output: "Tool 'csharpier' (version '1.2.6') was restored. Available commands: csharpier" /
+  "Restore was successful." — matches the recorded success shape at
+  docs/features/archive/2026-08-07-quickfiler-keyboard-action-contract-defects-445/evidence/baseline/dotnet-tool-restore.2026-08-22T09-18.md.
+
+## Output Summary
+
+Both steps succeeded: repo-local .NET SDK 8.0.205 installed for this worktree; CSharpier 1.2.6
+restored via dotnet-tools.json manifest, exit code 0, matching the archived precedent's success
+text verbatim.

docs/features/active/kastringasync-keyequals-contains-offset-583/evidence/baseline/kbdactions-baseline.md

@@ -0,0 +1,38 @@
+# KbdActionsTests Baseline (P0-T9)
+
+- Timestamp: 2026-09-13T01-05
+- Command: <resolved vstest executable> QuickFiler.Test\bin\Debug\QuickFiler.Test.dll
+  /InIsolation /Settings:scripts\vscode\TaskMaster.cli.runsettings
+  "/TestCaseFilter:FullyQualifiedName~KbdActionsTests"
+- EXIT_CODE: 0
+
+## Verbatim result
+
+```
+Test Run Successful.
+Total tests: 4
+     Passed: 4
+ Total time: 1.2679 Seconds
+```
+
+## Per-class reporting
+
+| Class | Total | Passed | Failed | Exit |
+|---|---|---|---|---|
+| KbdActionsTests | 4 | 4 | 0 | 0 |
+
+Individual tests: Add_WhenSourceAndStoredKeysAreDistinct_DoesNotTreatSubstringAsDuplicate,
+Add_WhenSourceAndStoredKeyAreExactDuplicate_ThrowsArgumentException,
+EnumerableConstructor_WhenStoredKeysDifferButKeyEqualsOverlaps_DoesNotThrow,
+FilterKeys_WhenDistinctStoredKeysCoexist_PreservesKeyboardMatchingSemantics (the pinned test).
+
+## Output Summary
+
+Exit code 0; verdict "Test Run Successful."; 4 Passed, 0 Failed for the KbdActionsTests class,
+including the pinned test FilterKeys_WhenDistinctStoredKeysCoexist_PreservesKeyboardMatchingSemantics.
+This baseline count (4) is expected to differ from the archived precedent's count of 3 on
+2026-08-22 (docs/features/archive/2026-08-07-quickfiler-keyboard-action-contract-defects-445/evidence/baseline/vstest-baseline.2026-08-22T09-18.md),
+because one test method (Add_WhenSourceAndStoredKeyAreExactDuplicate_ThrowsArgumentException or
+a sibling) has been added to the pinned file since that baseline was recorded; per the plan's
+own acceptance text this task's count is not compared against that archived figure. No file was
+diffed to obtain this result; it is derived solely from the test-run outcome.

docs/features/active/kastringasync-keyequals-contains-offset-583/evidence/baseline/msbuild-analyzers.md

@@ -0,0 +1,34 @@
+# MSBuild Analyzer Rebuild (Baseline)
+
+- Timestamp: 2026-09-13T00-30
+- Command: MSBuild.exe (VS18) TaskMaster.sln /t:Rebuild /m /p:Configuration=Debug
+  "/p:Platform=Any CPU" /p:EnableNETAnalyzers=true /p:EnforceCodeStyleInBuild=true
+  /flp:logfile=<detailed-file-log>;verbosity=detailed
+- EXIT_CODE: 0
+
+## Verdict line
+
+```
+Build succeeded.
+    0 Warning(s)
+    0 Error(s)
+```
+
+## Log-line counts (from the detailed file logger)
+
+- "Skipping target ... CoreCompile" occurrences: 0
+- "CoreCompile:" occurrences: 130 (proves the rebuild was not vacuous)
+- Total warning count: 0 (console verdict "0 Warning(s)"; no analyzer/compiler warning lines
+  present in the detailed log for this run — the five System.Reactive
+  PackagesConfigCheck.targets target-invocation trace lines present in the log are target-graph
+  trace lines, not warning diagnostics, and none is followed by a warning-severity message text)
+
+## Output Summary
+
+Exit code 0; verdict "Build succeeded."; 0 "Skipping target CoreCompile" occurrences; 130
+"CoreCompile:" occurrences (non-vacuous rebuild); recorded warning count is 0, which is the
+ceiling P5-T3 compares against. This differs numerically from the archived precedent's 5
+System.Reactive packages.config warnings at
+docs/features/archive/2026-08-07-quickfiler-keyboard-action-contract-defects-445/evidence/baseline/msbuild-analyzers.2026-08-22T09-21.md,
+but is consistent in kind (0 skip / >=9 CoreCompile / 0 errors); the numeric warning count is
+recorded as observed rather than assumed to match the archived figure.

docs/features/active/kastringasync-keyequals-contains-offset-583/evidence/baseline/msbuild-nullable.md

@@ -0,0 +1,27 @@
+# MSBuild Nullable Rebuild (Baseline)
+
+- Timestamp: 2026-09-13T00-35
+- Command: MSBuild.exe (VS18) TaskMaster.sln /t:Rebuild /m /p:Configuration=Debug
+  "/p:Platform=Any CPU" /p:TreatWarningsAsErrors=true
+  /flp:logfile=<detailed-file-log>;verbosity=detailed
+- EXIT_CODE: 0
+
+## Verdict line
+
+```
+Build succeeded.
+    0 Warning(s)
+    0 Error(s)
+```
+
+## Log-line count
+
+- "Skipping target ... CoreCompile" occurrences: 0
+
+## Output Summary
+
+Exit code 0; verdict "Build succeeded."; "Skipping target CoreCompile" count of exactly 0
+(141 "CoreCompile:" occurrences, confirming the rebuild was not vacuous). Matches the recorded
+shape (0 skip / 0 errors) at
+docs/features/archive/2026-08-07-quickfiler-keyboard-action-contract-defects-445/evidence/baseline/msbuild-nullable.2026-08-22T09-23.md.
+No nullable opt-in property (Nullable=enable) was passed, per the Command Reference.