Using --flags-dir on (third-party) sf plugins does not work #3493
Description
Summary
While I can successfully use the --flags-dir on core plugins, it does not work anymore with my sf plugin.
The --dev-debug shows the preparse hook was run in both cases, but the flag values are not set in my sf plugin sfdx-plugin-source-read and this Minimal Reproducible Example (MRE):
myflags/metadata:
Profile:Admin
Profile:Standard
Using the official sf project retrieve start:
sf project retrieve start --flags-dir myflags --dev-debug
# DEBUG (sf:oclif:@salesforce/cli:hooks:preparse): Returning argv: --flags-dir myflags --metadata Profile:Admin --metadata Profile:StandardUsing my plugin sf crud-mdapi read: flags.metadata is undefined
sf crud-mdapi read --flags-dir myflags --dev-debug
# DEBUG (sf:oclif:@salesforce/cli:hooks:preparse): Returning argv: --flags-dir myflags --metadata Profile:Admin --metadata Profile:StandardSteps To Reproduce
I've created a Minimal Reproducible Example (MRE): https://github.com/mdapi-issues/mre-sf-plugin-flags-dir
Expected result
The flag values should be set correctly when using --flags-dir.
Actual result
The flag values are set to the default value.
Additional information
Here is the initial bug report for my sf plugin: amtrack/sfdx-plugin-source-read#159
System Information
{
"architecture": "darwin-arm64",
"cliVersion": "@salesforce/cli/2.120.3",
"nodeVersion": "node-v24.13.0",
"osVersion": "Darwin 25.2.0",
"rootPath": "/Users/john.doe/.local/lib/node_modules/@salesforce/cli",
"shell": "zsh",
"pluginVersions": [
"@oclif/plugin-autocomplete 3.2.39 (core)",
"@oclif/plugin-commands 4.1.38 (core)",
"@oclif/plugin-help 6.2.36 (core)",
"@oclif/plugin-not-found 3.2.73 (core)",
"@oclif/plugin-plugins 5.4.54 (core)",
"@oclif/plugin-search 1.2.36 (core)",
"@oclif/plugin-update 4.7.16 (core)",
"@oclif/plugin-version 2.2.36 (core)",
"@oclif/plugin-warn-if-update-available 3.1.54 (core)",
"@oclif/plugin-which 3.2.42 (core)",
"@salesforce/cli 2.120.3 (core)",
"agent 1.26.5 (core)",
"apex 3.9.5 (core)",
"api 1.3.7 (core)",
"auth 4.1.2 (core)",
"data 4.0.67 (core)",
"deploy-retrieve 3.24.7 (core)",
"info 3.4.100 (core)",
"limits 3.3.74 (core)",
"marketplace 1.3.8 (core)",
"org 5.9.59 (core)",
"packaging 2.24.7 (core)",
"schema 3.3.90 (core)",
"settings 2.4.54 (core)",
"sobject 1.4.81 (core)",
"telemetry 3.6.71 (core)",
"templates 56.4.2 (core)",
"trust 3.7.113 (core)",
"user 3.6.46 (core)"
]
}