[feat] Front-end recovery UI for failed indexing after successful on-chain tx

[realproject7]

Problem

When a storyline/plot tx succeeds on-chain but the indexer API call fails (500, network error, browser crash), the user sees an error with no way to retry. The on-chain tx is permanent but the DB record is missing. The backfill cron will eventually catch it, but it won't have client-side metadata (genre, language, content fallback).

Reference Implementation

dropcast has a battle-tested pattern for this exact scenario:

• hooks/useCreateIntent.ts — localStorage-based intent storage with tx hash persistence + retry logic
• app/create/page.tsx (lines ~3346–3485) — Recovery modal UI ("Finalize Campaign" / "Resume Creation")
• hooks/useFundCampaign.ts — Transaction error parsing (distinguishes user-rejected vs sent-but-failed)

Key pattern (from dropcast):

1. Before tx: Save intent to localStorage (content, metadata, indexer route)
2. After tx confirms: Persist tx hash to localStorage
3. Indexer call: Attempt POST to indexer API
4. If indexer fails: Intent stays in localStorage with error + retry count
5. On page reload: Recovery UI appears — "Your story was published on-chain but indexing failed. Retry?"
6. User clicks retry: Re-sends the indexer POST with the same tx hash + metadata
7. On success: Clear localStorage intent, redirect to story page
8. 409 / duplicate: Treat as idempotent success (indexer upserts by tx_hash anyway)

Implementation

1. Create src/hooks/usePublishIntent.ts

localStorage-based intent that tracks:

interface PublishIntent {
  txHash: string | null;
  content: string;
  metadata: Record<string, string>;  // genre, language, etc.
  indexerRoute: string;
  uploadKeyPrefix: string;
  createdAt: number;
  retryCount: number;
  lastError: string | null;
}

• saveIntent() — called before wallet confirmation
• persistTxHash(hash) — called after tx confirms
• clearIntent() — called after successful indexing
• readPendingIntent() — check for unfinished intents on page load

2. Integrate into usePublish.ts

Wire the intent lifecycle into the existing 5-state flow:

• Before step 2 (confirming): saveIntent()
• After step 3 (pending → receipt): persistTxHash(hash)
• After step 4 (indexing success): clearIntent()
• On indexer error: keep intent, set error

3. Recovery UI on create/chain pages

On mount, check readPendingIntent(). If a pending intent exists (has txHash but indexer never succeeded):

• Show a recovery banner/modal: "Your previous story was published on-chain but indexing failed"
• Show tx hash (linked to explorer)
• "Retry Indexing" button → re-sends POST to indexer with saved metadata
• "Dismiss" button → clears intent (user accepts backfill cron will handle it, minus metadata)
• Max retry count (5) with warning after exceeded

4. Error classification

• User rejected tx: Clear intent immediately (no recovery needed)
• Tx sent but receipt poll failed: Persist intent with txHash, show recovery
• Tx confirmed, indexer 500/network error: Persist intent, show recovery
• Indexer 409 / duplicate: Treat as success, clear intent

Files to modify

• src/hooks/usePublishIntent.ts — new: localStorage intent management
• src/hooks/usePublish.ts — integrate intent lifecycle
• src/app/create/page.tsx — add recovery UI on mount
• src/app/story/[storylineId]/chain/page.tsx — add recovery UI for plot chaining too

Reference files (dropcast — read these for the full pattern)

• /Users/cho/Projects/dropcast/hooks/useCreateIntent.ts
• /Users/cho/Projects/dropcast/hooks/useFundCampaign.ts
• /Users/cho/Projects/dropcast/app/create/page.tsx (lines ~3346–3485)

Acceptance criteria

• Intent saved to localStorage before wallet confirmation
• Tx hash persisted after on-chain confirmation
• Intent cleared after successful indexing
• Recovery UI appears on page reload when pending intent exists
• Retry button re-sends indexer POST with all metadata (genre, language, content)
• Dismiss button clears the intent
• User-rejected tx clears intent (no false recovery)
• Works for both storyline creation and plot chaining
• npm run typecheck passes

[realproject7]

The work that had started for this issue was based on the design overhaul from #277. That overhaul is now being reverted in #281, so the current in-progress branch/history for #267 should be treated as stale.

Please restart #267 from a fresh branch after #281 is merged.