fix: resolve final 4 bugs before convergence

[GT-610]

Bug fixes:

• Aria2RpcClient.close(): completeError all pending completers with ConnectionFailedException before clearing (callers were hanging 10s then getting wrong TimeoutException instead)
• TaskActionDialogs: fix double-counting in outer catch — subtract already-counted success/skipped from remaining tasks.length
• TaskDetailsDialog: add outerContext.mounted guard before accessing outerContext.read() in timer callback (prevents crash if underlying page is disposed while timer fires)
• BuiltinInstanceService._buildArgs: use _resolveEffectiveDhtListenPort for --dht-listen-port instead of raw settings value (ensures valid port range 1-65535 and handles String→int parsing, matching UPnP port resolution)

Summary by CodeRabbit

Bug Fixes

• Corrected task failure counting to properly account for already-processed tasks and partial progress
• Added mounted-context checks to prevent operations after dialog disposal
• WebSocket RPC requests now fail properly instead of hanging when connection closes
• Improved DHT listen port resolution and validation

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: 4daa4ed1-3aea-418c-a4eb-a090166001b0

📥 Commits

Reviewing files that changed from the base of the PR and between 0624ca5 and 8a9f331.

📒 Files selected for processing (4)

• lib/pages/download_page/components/task_action_dialogs.dart
• lib/pages/download_page/components/task_details_dialog.dart
• lib/services/aria2_rpc_client.dart
• lib/services/builtin_instance_service.dart

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📝 Walkthrough

Walkthrough

The PR adds four targeted defensive improvements: fixing task failure accounting when exceptions occur mid-batch, guarding async peer-fetch dialogs against disposed contexts, failing pending RPC requests on WebSocket close instead of hanging, and validating DHT port configuration through a resolver function.

Changes

Defensive fixes and safeguards across UI and service layers

Layer / File(s)	Summary
Download page dialog error handling and cleanup lib/pages/download_page/components/task_action_dialogs.dart, lib/pages/download_page/components/task_details_dialog.dart	TaskActionDialogs._performActionForInstance computes additional failures only from uncounted tasks (avoiding double-counting partial progress), and TaskDetailsDialog.showTaskDetailsDialog exits early if the dialog context unmounts before async peer fetching.
Aria2 RPC client lifecycle and DHT configuration lib/services/aria2_rpc_client.dart, lib/services/builtin_instance_service.dart	WebSocket close() completes all pending RPC completers with ConnectionFailedException instead of abandoning them, and builtin instance startup validates the DHT listen port through _resolveEffectiveDhtListenPort(settings) instead of direct settings fallback.

Possibly related PRs

• GT-610/setsuna#80: Broader WebSocket connection/close behavior updates in Aria2RpcClient overlap with this PR's pending-request completion logic.
• GT-610/setsuna#74: Refactors WebSocket notification subsystem and teardown cleanup in the same aria2_rpc_client.dart close-path area.
• GT-610/setsuna#75: Related Aria2 RPC lifecycle changes including shutdown RPC handling in instance stopping.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 inconclusive)

Check name	Status	Explanation	Resolution
Title check	❓ Inconclusive	The title 'fix: resolve final 4 bugs before convergence' is vague and generic, using non-descriptive phrasing that does not convey meaningful information about specific bugs being fixed.	Replace the generic title with specific bug descriptions, e.g., 'fix: prevent WebSocket RPC timeouts and improve task counting/port validation' to clearly summarize the key fixes.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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