Allow user to set custom user agent

[sunkup]

Purpose

Enable user to add custom user agent per subscription.

Short description

• add custom user agent column to subscription table
• add text fields in AddSubscriptionScreen and EditSubscriptionScreen
• save the UI changes to the database through AddSubscriptionModel and EditSubscriptionModel
• load and save the custom user agent string from/to json export
• use a hilt assisted factory to create AppHttpClient
• log used custom user agent at validation
• use ktor's user agent plugin to set the user agent instead of the interceptor

Note:
The network interceptor approach introduced with the switch to ktor would have never worked. Kind of nice we notice it before releasing that. When I checked the user agent string with the android studio network inspector it simply said ktor-client or similar. Now with the ktor user agent plugin it actually sends the right user agent.

Checklist

• The PR has a proper title, description and label.
• I have self-reviewed the PR.
• I have added documentation to complex functions and functions that can be used by other modules.
• I have added reasonable tests or consciously decided to not add tests.

[sunkup]

@ArnyminerZ This is really a rushed minimal implementation. During the weekend please take a proper look and test everything well. I think it should work out, but I did for example not test the import/export. I would leave the extra microsoft user agent for a separate PR.

[ArnyminerZ]

Migration works correctly, and so does import-export. Only major issue I see is the field emptying issue.

Network inspection shows the correct User Agent:

Screenshot

[Copilot]

Pull Request Overview

This PR enables users to set custom user agents per subscription to better handle servers that require specific user agent strings for access. This addresses the issue where the ktor-client default user agent was being sent instead of the intended custom one.

• Add custom user agent support to subscription data model and UI screens
• Switch from OkHttp interceptor to ktor UserAgent plugin for proper user agent handling
• Implement dependency injection factory pattern for AppHttpClient to support per-subscription configuration

Reviewed Changes

Copilot reviewed 18 out of 18 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
strings.xml	Add UI strings for custom user agent input field
SubscriptionSettingsComposable.kt	Add custom user agent text field to subscription settings
EnterUrlComposable.kt	Add custom user agent input to URL entry form with advanced settings section
EditSubscriptionScreen.kt	Pass custom user agent data through edit subscription flow
AddSubscriptionScreen.kt	Pass custom user agent data through add subscription flow
ValidationUseCase.kt	Update validation to use custom user agent via factory pattern
SubscriptionSettingsUseCase.kt	Add custom user agent state management and validation logic
EditSubscriptionModel.kt	Add custom user agent persistence for existing subscriptions
AddSubscriptionModel.kt	Add custom user agent persistence for new subscriptions
Subscription.kt	Add customUserAgent field to database entity and JSON serialization
AppDatabase.kt	Bump database version for schema migration
ProcessEventsTask.kt	Use factory to create HTTP client with subscription's custom user agent
HttpUtils.kt	Refactor authentication check to general protocol validation
AppHttpClient.kt	Convert to factory pattern with ktor UserAgent plugin instead of interceptor

Comments suppressed due to low confidence (1)

app/src/main/java/at/bitfire/icsdroid/ui/views/EnterUrlComposable.kt:316

• The parameter name supportsAuthentication is misleading since it's being passed validUrlInput. Consider renaming the parameter to match its actual purpose or verify the correct value is being passed.

        error,

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}

[sunkup]

@ArnyminerZ

Please take a look. I incorporated the requested changes and:

• used a normal text field for the custom user agent input - I think we should leave ResourceInput reserved for the two different subscription address values.
• Renamed the "supportsAuthentication" notion to "acceptedProtocol", because it actually checks just that and we can use it more broadly.
• moved the custom user agent textfield into the hidden content section when adding URL
• added an extra spacer for consistency
• remove the companion object completely in AppHttpClient.
• Only when adding subscription - hide the custom user agent textfield within another toggle option with UI logic only

[ArnyminerZ]

Some small changes, but my problem is with the redesign, I mean, moving it into the Enter url composable. I don't understand why doubling the field:

It's here	and here

For me it's a bit odd to double the field, since they are also different (one has a toggle, and the other one doesn't)

[sunkup]

hmm yes. Makes absolute sense. Thank you for the thorough review 👍

[ArnyminerZ]

Got to a quite big PR, but works well for me.