[johnml1135]

Fixes LT-22840.

Problem

Developer tooling wrote per-user overrides under HKCU\SOFTWARE\SIL: FieldWorks\9\RootCodeDir, RootDataDir, ProjectsDir, Icu<ver>DataDir, plus the silfw:// handler and the SilEncConverters40 and EncodingConverterRepository keys. The installed app reads HKCU before HKLM, so an installed FLEx could load code, data and ICU from a dev worktree. Installed 9.3.10 then failed to create AiAnalysisExportListener while the Hermit Crab trace fix was being validated, and silfw:// links launched the dev exe.

Design

Rule: a dev run never writes shared (HKCU) state, and a run never trusts a leftover HKCU path that points into a source tree.

A run is a "dev run" when FwDirectoryFinder.FindDevDistFiles finds a DistFiles folder with a FieldWorks.sln in an ancestor of the running assembly (already on main since #1093). Otherwise it is installed. A "source-tree path" is a path under a directory that contains FieldWorks.sln (FwDirectoryFinder.IsSourceTreePath).

Precedence (first match wins):

Item	Dev run	Installed run
Code, data dirs	running tree's DistFiles > HKCU > HKLM > default	HKCU (ignored if source-tree path) > HKLM > default
ICU data dir	ICU_DATA env > running tree's DistFiles\Icu<ver> > HKCU > HKLM	ICU_DATA env > HKCU > HKLM; a registry dir that does not exist or is a source-tree path is skipped
Projects dir	in-memory choice for this session > HKCU ProjectsDir > HKLM > <DataDir>\Projects	HKCU ProjectsDir > HKLM > <DataDir>\Projects

Projects are deliberately shared between dev and installed runs so developers see the same projects. ProjectsDir is NOT filtered by the source-tree rule. The only change is write side: a dev run keeps a projects-folder change in memory only (ProjectsDirectory setter) and never writes or deletes HKCU. An installed run still persists it as before.

What changed:

• Writers removed: the unused setRegistryValues/setKeysInHKCU MSBuild targets (no callers in the repo) are deleted; the test initializer no longer writes RootCodeDir/RootDataDir; the launch-preflight skill script Resolve-FieldWorksDevRegistry.ps1 is now read-only, also with -Force (it just runs the repair script with -WhatIf).
• Readers hardened: FwDirectoryFinder.GetDirectory and the Paratext plugin finder skip HKCU RootCodeDir/RootDataDir under a source tree and fall back to HKLM/default; Convert.cs ignores a source-tree v8 RootCodeDir; FwUtils.InitializeIcu goes through ChooseIcuDataDir and ignores a missing or source-tree Icu*DataDir. The dev ICU probe now also requires FieldWorks.sln.

Production vs dev-only impact

Production (installed) code paths changed: the source-tree filters (no effect unless an installed FLEx sits beside a FieldWorks.sln), skipping a nonexistent registry ICU directory in InitializeIcu (previously set ICU_DATA to a missing folder), and the Convert.cs v8 RootCodeDir check, which also catches path exceptions. Everything else is dev-only (build targets, test initializer, skill scripts, and the in-memory projects setter, which is active only in a source-tree run).

Repair script (Build/Repair-DeveloperRegistry.ps1)

Removes existing HKCU values that point into a source tree: RootCodeDir, RootDataDir, Icu*DataDir, SilEncConverters40\RootDir/DeveloperPluginDir, EncodingConverterRepository\Registry, and the silfw handler key if its exe is in a source tree. It keeps values outside source trees and keeps ProjectsDir, which dev and installed runs share.

# close FieldWorks first
.\Build\Repair-DeveloperRegistry.ps1 -WhatIf   # preview only
.\Build\Repair-DeveloperRegistry.ps1           # apply

Supports -WhatIf/-Confirm. It cannot identify a checkout whose FieldWorks.sln was deleted or moved.

Gotchas

• Installed 9.3.10 needs the repair script once. The shipped binary has the old reader, which this PR cannot change; only builds after this one ignore source-tree paths.
• Older branches can re-pollute. A dev build or test run from a branch without this change still writes these keys. Re-run the script after using one.
• A checkout with its FieldWorks.sln removed is not recognised as a source tree.
• Dev runs no longer remember a projects folder chosen in the UI across launches (process only); a projects folder already set in HKCU (including one inside a dev tree) is still used by both. An older dev build may have left HKCU ProjectsDir pointing into a worktree; installed FLEx follows it, as before.
• Separate ICU dev-probe initialisation-order issue LT-22768 is not addressed.

Tests

• FwDirectoryFinderTests (dummy registry): reader fallback matrix including a tree with no DistFiles; non-source user override wins; test initializer writes nothing; ProjectsDirectory set from a source-tree run does not persist; both run orders (dev then installed, installed then dev); a text scan checks the build scripts write no registry keys; a source-tree HKCU ProjectsDir is honoured by both dev and installed runs.
• IcuDataDirChoiceTests: tree first, missing/source-tree keys skipped, HKLM fallback.
• ParatextLexiconPluginDirectoryFinderTests: code/data fallback, source-tree ProjectsDir honoured, installed values win; on a temporary HKCU subkey, deleted in TearDown.
• Build/Repair-DeveloperRegistry.Tests.ps1: 22 checks (keeps ProjectsDir) on PowerShell 5.1 and 7 (mocked registry): selective cleanup, preview, malformed/non-source values, missing keys, silfw/EC keys, read-only preflight.
• Final run: FwUtilsTests 474 passed, 0 failed (476 discovered, 2 not executed); FwParatextLexiconPluginTests 38 passed, 0 failed; Pester file 22 checks passed. Not run: full FieldWorks suite, installer packaging, Convert.cs in isolation (no tests).

Manual verification

1. Installed after dev: seed HKCU RootCodeDir/RootDataDir/Icu<ver>DataDir with worktree paths, run -WhatIf (it lists them), run it for real, then launch installed FLEx; it loads from Program Files and your projects list is unchanged.
2. Dev after installed: run installed FLEx once, snapshot HKCU\SOFTWARE\SIL, launch Output\Debug\FieldWorks.exe from two worktrees; each uses its own DistFiles and ICU, and the HKCU snapshot diff is empty (including after changing the projects folder in the dev run).
3. Clean user hive: launch each of dev and installed with no keys; dev uses the tree, installed uses HKLM/default.

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This change is 

[github-actions]

NUnit Tests

    1 files  ± 0      1 suites  ±0   10m 35s ⏱️ +13s
6 610 tests +15  6 525 ✅ +15  85 💤 ±0  0 ❌ ±0 
6 619 runs  +15  6 534 ✅ +15  85 💤 ±0  0 ❌ ±0 

Results for commit e477a76. ± Comparison against base commit a90754c.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 61.53846% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 39.49%. Comparing base (a90754c) to head (e477a76).

Files with missing lines	Patch %	Lines
Src/Common/FwUtils/FwDirectoryFinder.cs	61.53%	6 Missing and 4 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1183   +/-   ##
=======================================
  Coverage   39.49%   39.49%           
=======================================
  Files        1537     1537           
  Lines      354392   354417   +25     
  Branches    41058    41064    +6     
=======================================
+ Hits       139974   139985   +11     
- Misses     185044   185056   +12     
- Partials    29374    29376    +2     

Files with missing lines	Coverage Δ
Src/Common/FwUtils/FwDirectoryFinder.cs	69.29% <61.53%> (-0.58%)	⬇️

... and 3 files with indirect coverage changes

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[johnml1135]

Update: removed the unused setRegistryValues/setKeysInHKCU targets, which wrote RootCodeDir/RootDataDir/ProjectsDir, ICU, EC and silfw:// keys to HKCU. A source-tree run keeps a changed projects folder in memory only and never writes HKCU; ProjectsDir is still shared with installed FLEx and is not filtered, so existing dev-tree project folders keep working. InitializeIcu prefers the running tree and ignores missing or source-tree registry ICU dirs. The Paratext plugin finder skips source-tree HKCU RootCodeDir/RootDataDir, and Convert.cs skips a source-tree v8 RootCodeDir. Repair-DeveloperRegistry.ps1 also clears the source-tree SilEncConverters40, EncodingConverterRepository and silfw:// keys, and keeps ProjectsDir. Both run orders are tested (FwUtilsTests 474, Paratext plugin tests 38, repair script 22 checks, all passing); installed 9.3.10 still needs the script once.