MATLAB Settings Migration

Diff MATLAB settings between two releases and automatically update any .m file that configures MATLAB settings (via .PersonalValue or .TemporaryValue assignments) so that setting paths point to the correct locations in the target release. Works with startup scripts, team preference files, test setup scripts, deployment configs, or any code that programmatically sets MATLAB settings.

When To Use

• Upgrading MATLAB releases and existing .m scripts set PersonalValue or TemporaryValue on settings whose paths changed between releases
• Setting paths moved, were renamed, or had their value types changed between the source and target release
• Migrating startup scripts, team preference files, test setup, or deployment configs to a newer (or older) MATLAB release

When Not To Use

• The .m file does not set any MATLAB settings (s.PersonalValue / s.TemporaryValue assignments)
• You want to change MATLAB preferences interactively (use the Preferences dialog instead)
• You need to migrate Simulink or toolbox-specific settings (this skill covers core MATLAB settings only)

Arguments

• <script-path> — (required) Path to any .m file that sets PersonalValue/TemporaryValue on MATLAB settings
• [from:R20XXy] or [from:/path/to/MATLAB/R20XXy] — (optional) Source release the script was written for. Accepts either a release name (e.g., R2025b) which is resolved to the platform default install location, or a full path to a MATLAB installation root. If omitted, auto-detected from script content.
• [to:R20XXy] or [to:/path/to/MATLAB/R20XXy] — (optional) Target release to migrate to. Accepts either a release name or a full path to a MATLAB installation root. If omitted, defaults to the latest installed MATLAB release on this machine.

Examples:

/matlab-settings-migrate ~/startup.m
/matlab-settings-migrate ~/startup.m from:R2025b to:R2026a
/matlab-settings-migrate ~/startup.m to:R2025a
/matlab-settings-migrate ./test/setup_prefs.m from:/opt/matlab/R2025b to:/opt/matlab/R2026a
/matlab-settings-migrate ~/team_settings.m from:/network/apps/MATLAB/R2024b to:R2026a

Default behavior (no from/to): Detect the source release from the script, then migrate to the newest installed MATLAB release. If you want to migrate to an older release (downgrade), specify to: explicitly.

Argument parsing

Parse the arguments string to extract:

1. The script path (first argument that looks like a file path)
2. Optional from: value — either a release name (R20XXy) or a full path (/path/to/MATLAB/R20XXy)
3. Optional to: value — either a release name (R20XXy) or a full path (/path/to/MATLAB/R20XXy)

Path resolution: If the value after from: or to: starts with /, ~, or a drive letter (e.g., C:\), treat it as a full path to a MATLAB installation root. Otherwise, treat it as a release name and resolve it to a full path using the platform-specific default install location (determined in Phase 0).

If only the script path is provided, run Phase 0 (auto-discovery).

Phase 0: Auto-detect MATLAB installations (skip if both roots provided)

If from: or to: are missing, auto-detect installed MATLAB releases. Read references/auto-detect-installations.md for the full procedure (platform detection, folder scanning, source/target resolution). Key behavior:

• Detect platform via uname -s → determines default install directory
• List installed releases by scanning the default directory for R20* folders
• Source release: detected from script content (filename hints, comments, or key matching against SO/DLLs)
• Target release: defaults to the latest installed release (unless to: was explicit)
• Downgrade requires explicit to: — default always goes to the latest

How to execute

Performance constraint: Minimize tool calls. Target ≤6 total bash/read invocations for the entire migration. Batch aggressively — never check settings one-by-one in separate commands. Phase 1 setup (find libs, extract strings, diff) and Phase 2 (read startup script) are independent and MUST run in parallel.

Phase 1: Build the settings change map

Produce the full change map (renamed, moved, removed, added) between releases.

Step 1: Validate paths and determine source format

Check for .hpp source files first (available on some Linux installs):

OLD_HPP=<old-matlab-root>/toolbox/matlab/settings/matlab_factory_settings
NEW_HPP=<new-matlab-root>/toolbox/matlab/settings/matlab_factory_settings

If .hpp files exist in both, use the HPP path (Step 2A). If .hpp files do NOT exist (common on Windows where they are compiled to DLLs), use the DLL path (Step 2B).

To locate the shared library (extension depends on platform detected in Phase 0):

# Linux: .so | macOS: .dylib | Windows: .dll
find "<matlab-root>/bin" -path "*factory_settings*" -name "mwmatlab_factory_settings.*" 2>/dev/null
# Typical paths:
#   Linux:   <root>/bin/glnxa64/factory_settings/compute/settings/matlab/mwmatlab_factory_settings.so
#   macOS:   <root>/bin/maci64/factory_settings/compute/settings/matlab/mwmatlab_factory_settings.dylib
#   Windows: <root>/bin/win64/factory_settings/compute/settings/matlab/mwmatlab_factory_settings.dll

Step 2A: HPP path (plain-text source available)

File-level diff

Compare which .hpp files exist in each release:

ls "$OLD_HPP"/*.hpp | xargs -I{} basename {} | sort > /tmp/hpp_old.txt
ls "$NEW_HPP"/*.hpp | xargs -I{} basename {} | sort > /tmp/hpp_new.txt
comm -23 /tmp/hpp_old.txt /tmp/hpp_new.txt   # files only in OLD (removed)
comm -13 /tmp/hpp_old.txt /tmp/hpp_new.txt   # files only in NEW (added)

For any NEWLY added .hpp file, read it and list all settings it defines. For any REMOVED .hpp file, read it from OLD and list all settings.

Extract all setting names with namespace context

For EACH .hpp file that exists in BOTH releases, extract addSetting and addGroup lines:

grep -n "addSetting\|addGroup" "$OLD_HPP/factorysettings_XXXX.hpp"
grep -n "addSetting\|addGroup" "$NEW_HPP/factorysettings_XXXX.hpp"

The group hierarchy gives you the full setting path:

• matlabFactoryGroup.addGroup("editor") → matlab.editor
• editor.addGroup("spelling") → matlab.editor.spelling
• spelling.addSetting("CheckSpelling") → matlab.editor.spelling.CheckSpelling

Diff setting names within each file

For each shared .hpp file:

1. Identify settings REMOVED (in old, not in new)
2. Identify settings ADDED (in new, not in old)
3. For removed+added pairs in the same namespace, determine if it's a RENAME (same group, different key name) vs. truly removed/added

Extract type and validation for changed settings

For every setting that is renamed, moved, or split, extract the full addSetting block (not just the name line) from BOTH releases — capture FactoryValue, ValidationFcn, and any ValueValidator:

grep -B 5 -A 8 'spelling.addSetting("CheckSpelling"' "$NEW_HPP/factorysettings_editor.hpp"

See references/settings-internals.md for reading types from these fields and for the type-transition mapping rules (same type, type changed, type narrowed). Confirm the result against the target runtime before translating a value — class(o.FactoryValue) is authoritative where the hpp is ambiguous.

Classify and determine moves

For settings that appear removed from one file and added to another file, classify as MOVED.

Optional — verify renames via JS panel source

If a rename is ambiguous from hpp alone, confirm by reading the JS panel source files.

Step 2B: DLL path (compiled binary — Windows/macOS/Linux without source)

When .hpp source files are not available, extract setting names and type information directly from the compiled factory settings library using strings. Read references/dll-path-extraction.md for the full procedure — it covers string table extraction, batch context verification, rename classification decision tree, and type extraction. Key principles:

• SO/DLL stores group names and key names as separate adjacent strings, NOT dotted paths — do NOT grep full paths
• Use grep -B40 -A5 for group context; the IMMEDIATE parent group (last lowercase name above the key) gives the runtime path
• String presence ≠ setting existence — confirm keys are in valid addSetting position, not just present as dead strings
• Before classifying as "Removed", search the entire target SO/DLL for partial key name matches (renames can cross groups)
• For type changes, use -A15 context to find ValidStringValues — never stringify boolean literals

Phase 2: Parse the user's script

Step 7: Read the script and identify all settings references

Read <script-path> and find every line that references a setting path. Users may use ANY variable name for the settings root — not just s. Common patterns:

1. Direct assignment — s.matlab.editor.spelling.CheckSpelling.PersonalValue = false;
2. Any variable name — prefs, mySettings, settings_root, etc.
3. Variable from settings — prefs = settings; then prefs.matlab...
4. Inside try-catch — nested fallbacks for cross-release compatibility; migrate every branch
5. Version-conditional — if isMATLABReleaseOlderThan("R2026a") ... else ... end; migrate both branches

Detection strategy:

1. Find the settings variable: look for = settings; or = matlab.settings.SettingsGroup or any variable used with .matlab. followed by known setting paths.
2. Extract the variable name (everything before .matlab.).
3. Extract the full setting path (everything between the variable and .PersonalValue, .TemporaryValue, or .FactoryValue).

Build a list of (line_number, variable_name, full_setting_path, assigned_value) tuples.

Step 8: Positively verify EACH script setting in the target release

This is the critical correctness gate. Do NOT rely solely on the diff/change map from Phase 1. For EVERY setting key extracted from the user's script, positively confirm it exists in the target release by grepping the target's hpp files or DLL.

HPP path (preferred — fast and definitive):

# Batch-verify ALL keys from the script in ONE command against target hpp files:
for key in Key1 Key2 Key3 ...; do
  echo "=== $key ==="; grep -r "addSetting(\"$key\"" "$NEW_HPP"/ || echo "NOT FOUND"
done

If addSetting("KeyName") is NOT found in any target hpp file, the setting does NOT exist in the target — regardless of what the Phase 1 diff said.

DLL path (when hpp unavailable): Use the addSetting context verification from Phase 1 Step 2B — the key must appear in valid definition position below its parent group.

Runtime confirmation (authoritative — required before classifying anything as Removed). Grep proves only that a string is present; hasSetting proves a setting is defined at a given path. Batch it over the script's keys:

s = settings;
s.matlab.<group>.hasSetting('<Key>')   % 1 = exists here, 0 = not here

Step 9: Classify each setting based on verification results

For each setting from the user's script, classify using BOTH the Phase 1 change map AND the Step 8 verification:

1. Unchanged — key found via addSetting in target at the same full path → no action
2. Renamed — key NOT found at old path, but Phase 1 change map identifies a rename → update key name
3. Moved — key found in target but under a different parent group → update full path
4. Removed with no replacement — key NOT found in target via Step 8, hasSetting returns 0 for every candidate group from the search below, AND no rename/move identified in Phase 1 → comment out
5. Already uses new path — key confirmed at same path → no action
6. Not found in target release — cannot confirm existence via addSetting grep AND the hasSetting search below is exhausted → treat as Removed, comment out. Do NOT leave it active — an unrecognized setting will error at runtime.

A vanished intermediate group does NOT mean the setting was removed — this is the most common failure in this skill. When a subgroup is retired the key usually survives one level up. Before classifying as Removed, run hasSetting on each candidate: the group with the subgroup dropped (a.b.suggestions.Key → test a.b), the parent's siblings, then the renamed key. "Removed" is correct only after all return 0.

Example: commandwindow.suggestions.ShowTypoSuggestions into R2025b+. The suggestions subgroup is gone, so the old path errors — but s.matlab.commandwindow.hasSetting('ShowTypoSuggestions') returns 1. Rewrite the path and keep the original logical value; commenting it out silently drops a preference the user still has.

Phase 3: Update the script

Step 10: Determine output file path

CRITICAL: Never overwrite the original file. Always write to a NEW file. Derive the output path automatically:

• Same directory as the original file
• Append the target release name before the extension
• If input is startup.m → write to startup_R2026a.m (same folder)
• If input is my_prefs.m → write to my_prefs_R2026a.m (same folder)
• If input is test/setup_settings.m → write to test/setup_settings_R2026a.m
• If the user provided a 4th argument as an explicit output path, use that instead

Do NOT ask the user for confirmation — just create the new file. The original is never touched.

Step 11: Apply transformations

For each setting that needs updating:

1. Simple rename/move (same type): Replace the old path with the new path in-place, keeping the original value.

   % Before (logical → logical, no type change):
   s.matlab.editor.displaysettings.OldName.PersonalValue = true;
   % After:
   s.matlab.editor.displaysettings.NewName.PersonalValue = true;
   

1b. Rename/move with type change: Replace the path AND translate the value to match the new type. You MUST use the allowed values discovered from the target DLL/hpp ValidStringValues (Phase 1 Step 6). Add a comment showing the original value for auditability.

% Before (logical → string enum {"auto","on","off"}):
s.matlab.editor.spelling.SpellingErrors.PersonalValue = false;
% After (ValidStringValues shows {"on","off","auto"}, so false maps to "off"):
s.matlab.editor.spelling.CheckSpelling.PersonalValue = "off";  % was: false (type changed logical→string)

Value translation rules when type changes from logical to string:

• MUST look up the ValidStringValues for the setting in the target DLL/hpp (Phase 1 Step 6). The -A15 context around the setting key in strings output shows the allowed values.
• Map true to the "enabled" value (typically "on") and false to the "disabled" value (typically "off") based on what ValidStringValues contains.
• 0 (numeric used as logical) → "off" or false depending on new type
• 1 (numeric used as logical) → "on" or true depending on new type
• Never guess the string value from the boolean literal — "false", "0", '0' are never valid setting values. Always use the actual allowed values from the target binary.
• If the mapping is ambiguous (e.g., factory default is "auto" and user had true), flag it with a % REVIEW: comment explaining the options so the user can choose

2. Try-catch blocks referencing old paths: If the script already has nested try-catch for the same setting, collapse them into a single assignment with the new path (remove the try-catch if only one path is needed for the target release). If the user wants cross-release compatibility, keep a try-catch with new path first, old path as fallback:

   try
       s.matlab.editor.spelling.CheckSpelling.PersonalValue = false;
   catch
       s.matlab.editor.spelling.SpellingErrors.PersonalValue = false;
   end
   

3. Version-conditional blocks: Update the condition and the paths in both branches.

4. Removed settings OR settings not found in target release: Comment out with explanation — both settings explicitly removed and those whose key cannot be found anywhere in the target release. Never leave an unverified setting active; it will error at runtime.

   % REMOVED in <new-release>: s.matlab.X.Y.Z no longer exists
   % s.matlab.X.Y.Z.PersonalValue = false;
   

   Also comment out any associated fprintf/disp line.

   First confirm the key is absent from every candidate group via the Step 9 hasSetting search. If found, this is a Moved setting — rewrite the path instead. Never justify a comment-out with "the group no longer exists"; that says nothing about the key.

Step 12: Preserve user intent

• Keep all fprintf/disp statements that document what each setting does
• Keep the user's chosen variable name (don't rename prefs to s)
• If the setting still exists in the target (same key name), KEEP that setting name. Do NOT substitute a different setting — even if another setting seems semantically related. The user's script sets LiveEditorInteractiveOutputs, so the output must set LiveEditorInteractiveOutputs (at its new path).
• Only translate the value if the type actually changed. Check class(o.FactoryValue) in the target (Phase 1 Step 2B). If it is still logical, keep true/false — converting to "on"/"off" errors at runtime. Translate to a string only when the target type is char/string.
• If you cannot determine the equivalent value with confidence, add a % REVIEW: comment with the available options.
• Keep comment blocks and section separators
• If a setting was split into multiple settings in the new release, add all new settings with appropriate values and add a comment explaining the split. If the split settings have different types, translate each independently.

Step 12b: Runtime validation of the output file (MANDATORY)

Run the output file in the target MATLAB to confirm zero runtime errors. Use mcp__matlab__evaluate_matlab_code if available; otherwise fall back to "<target-matlab-root>/bin/matlab" -batch "run('<output-file>')" via Bash.

If MATLAB reports errors:

1. For path errors ("Unrecognized method, property, or field"): the setting MOVED — do NOT comment it out. Find the correct new path: search the target SO for the key name, check its surrounding group context, and reconstruct the full path. Verify the new path with another MATLAB call.
2. For type errors ("invalid value"): the type changed. Query s.<path>.ValidStringValues in MATLAB to get accepted values, then translate.
3. For missing group errors (add-on settings like copilot): wrap in try-catch.
4. Fix the output file and re-run until MATLAB reports zero errors.

NEVER comment out a setting just because its path errors at runtime. A runtime path error means the setting MOVED (to a new intermediate group or restructured path) — it was NOT removed. Only classify as "removed" if the key name does not exist anywhere in the target SO/DLL. Runtime validation is mandatory and must not be skipped.

Step 13: Report changes and provide setup instructions

After writing the migrated file, present:

A) Migration summary:

## Migration Summary: <input-file> → <output-file>

### Updated (N settings)
- s.matlab.old.Path → s.matlab.new.Path (line 42)
- s.matlab.old.Path → s.matlab.new.Path (line 55) ⚠️ TYPE CHANGED: logical → string {"auto","on","off"}, value translated: false → "off"
- ...

### Already correct (N settings)
- s.matlab.editor.SaveFilesOnClickAway (line 15)
- ...

### Removed — requires manual review (N settings)
- s.matlab.X.Y.Z (line 67) — commented out
- ...

### Needs manual review — ambiguous type mapping (N settings)
- s.matlab.X.Y.Z (line 72) — old value `true` could map to "on" or "auto" (factory default is "auto")
- ...

### New settings available (not in your script)
- s.matlab.new.Setting — type: string, default: "auto"
- ...

B) Setup instructions (only if the file appears to be a startup script):

If the file is named startup.m or appears to be a startup/preferences script, provide deployment options. See references/settings-internals.md § "Startup deployment options" for the three options (replace, per-release dispatcher, symlink).

If the file is NOT a startup script, skip setup instructions and just report the output file path.

Key facts, change patterns, and type detection

See references/settings-internals.md for the full reference on factory settings file locations, type/validation extraction from addSetting blocks, legacy aliases, common change patterns (rename, reorganization, split, promotion, deletion, type change), type change mapping rules, and type detection from hpp source or DLL strings.

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