feat: implement issues #184, #185, #191, #192

#184 — Minimum contribution configurable at deploy time
- initialize() now accepts min_contribution: i128 (default 100 stroops)
- Stored in DataKey::MinContribution; contribute() reads from storage
- get_min_contribution() getter added
- Boundary tests: 99 stroops rejected, 100 accepted; custom min tests
- README documents deployment param and contract rules

#185 — update_metadata for campaign creators
- update_metadata(campaign_id, creator, new_metadata) added to contract
- Only original creator, before deadline, on active campaigns
- Emits MetadataUpdated event with old + new values
- Backend eventIndexer recognises Goal:MetaUpd topic and calls
  updateCampaignMetadata() to sync local DB
- CampaignEventType extended with metadata_updated

#191 — Multi-token campaign support (frontend + backend)
- CampaignRecord gains tokenBalances: Record<string, number>
- getCampaignTokenBalances() queries pledges table per asset_code
- getCampaign() now populates tokenBalances on every read
- Campaign type in frontend extended with tokenBalances
- CampaignCard shows per-token progress bars for multi-token campaigns
- CampaignDetailPanel adds token selector dropdown in pledge form

#192 — Deadline extension governance
- Campaign struct gains created_at: u64 (set on create_campaign)
- DataKey::ExtensionRequest(u64) and DataKey::ExtensionVote(u64, Address)
- ExtensionRequest struct stores new_deadline, requested_by, approval_count
- request_deadline_extension(): contributor-only, auto-approves requester,
  emits ExtensionRequested event, validates MAX_CAMPAIGN_DURATION_SECONDS
- approve_extension(): contributor-only, prevents double-vote, applies
  deadline when approval_count * 2 > contributor_count
- get_extension_request() getter for pending requests
- Full test suite: 38 tests passing (cargo test)

Author: joelpeace48-cell

README.md

@@ -57,10 +57,12 @@ Each campaign stores:
 - `creator`
 - `title`
 - `description`
-- `assetCode`
+- `acceptedTokens` — one or more Stellar asset codes the campaign accepts
+- `assetCode` — first accepted token (backward-compatibility alias)
 - `targetAmount`
 - `pledgedAmount`
 - `deadline`
+- `tokenBalances` — per-token pledge totals (`Record<assetCode, amount>`)
 
 Campaign states:
 
@@ -69,6 +71,59 @@ Campaign states:
 - `claimed` when the creator has claimed a funded vault
 - `failed` when deadline has passed without reaching the target
 
+## Contract rules
+
+### Minimum contribution (issue #184)
+
+The Soroban contract enforces a minimum contribution per pledge. The default is **100 stroops**. This is configurable at deploy time via `initialize(admin, min_contribution)`.
+
+```bash
+# Deploy with a custom minimum (e.g. 500 stroops)
+stellar contract invoke --id $CONTRACT_ID -- initialize \
+  --admin $ADMIN_ADDRESS \
+  --min_contribution 500
+```
+
+Contributions below the minimum are rejected with `"contribution below minimum"`.
+
+### Metadata updates (issue #185)
+
+A campaign creator can update the campaign metadata before the deadline:
+
+```bash
+stellar contract invoke --id $CONTRACT_ID -- update_metadata \
+  --campaign_id 1 \
+  --creator $CREATOR_ADDRESS \
+  --new_metadata "Updated description"
+```
+
+The contract emits a `MetadataUpdated` event containing both the old and new metadata values. The backend event indexer processes this event and updates local state automatically.
+
+### Deadline extension governance (issue #192)
+
+Any existing contributor can request a deadline extension:
+
+```bash
+stellar contract invoke --id $CONTRACT_ID -- request_deadline_extension \
+  --campaign_id 1 \
+  --caller $CONTRIBUTOR_ADDRESS \
+  --new_deadline <unix_timestamp>
+```
+
+Other contributors can vote to approve:
+
+```bash
+stellar contract invoke --id $CONTRACT_ID -- approve_extension \
+  --campaign_id 1 \
+  --caller $OTHER_CONTRIBUTOR
+```
+
+The extension is applied once **more than 50%** of unique contributors have approved. Constraints:
+
+- New deadline must be later than the current deadline
+- New deadline cannot exceed `MAX_CAMPAIGN_DURATION_SECONDS` (180 days) from the campaign creation timestamp
+- Reverts on claimed or canceled campaigns
+
 ## Mutation testing
 
 Mutation testing is used to verify that the test suite is effective at catching real bugs, not just achieving line coverage.

backend/src/services/campaignStore.ts

@@ -48,6 +48,7 @@ export interface CampaignRecord {
     externalLink?: string;
   };
   maxPerContributor?: number;
+  tokenBalances?: Record<string, number>;
 }
 
 export interface CampaignProgress {
@@ -479,7 +480,9 @@ export function getCampaign(campaignId: string): CampaignRecord | undefined {
         row.failed_at = row.deadline;
         db.prepare(`UPDATE campaigns SET failed_at = ? WHERE id = ?`).run(row.deadline, row.id);
     }
-    return rowToCampaign(row);
+    const campaign = rowToCampaign(row);
+    campaign.tokenBalances = getCampaignTokenBalances(campaignId);
+    return campaign;
   }
   return undefined;
 }
@@ -1097,6 +1100,83 @@ export function refundContributor(
  * @param limit - Maximum number of top contributors to return (default: 10).
  * @returns An array of {@link LeaderboardEntry} objects sorted by total pledged amount (descending).
  */
+/**
+ * Returns per-token pledged balances for a campaign (non-refunded only).
+ * Maps asset_code → total pledged amount for that token.
+ */
+export function getCampaignTokenBalances(campaignId: string): Record<string, number> {
+  const db = getDb();
+  const rows = db
+    .prepare(
+      `SELECT asset_code, COALESCE(SUM(amount), 0) AS balance
+       FROM pledges
+       WHERE campaign_id = ? AND refunded_at IS NULL
+       GROUP BY asset_code`,
+    )
+    .all(campaignId) as Array<{ asset_code: string; balance: number }>;
+
+  const result: Record<string, number> = {};
+  for (const row of rows) {
+    result[row.asset_code] = round(row.balance);
+  }
+  return result;
+}
+
+/**
+ * Partially updates a campaign record (title, description, metadata).
+ * Used internally and by the event indexer to apply on-chain metadata changes.
+ */
+export function updateCampaign(
+  campaignId: string,
+  patch: Partial<Pick<CampaignRecord, 'title' | 'description' | 'metadata'>>,
+): CampaignRecord {
+  const db = getDb();
+  const campaign = getCampaign(campaignId);
+  if (!campaign) {
+    throw Object.assign(new Error(`Campaign ${campaignId} not found`), { code: 'CAMPAIGN_NOT_FOUND' });
+  }
+
+  const updates: string[] = [];
+  const params: unknown[] = [];
+
+  if (patch.title !== undefined) {
+    updates.push('title = ?');
+    params.push(patch.title);
+  }
+  if (patch.description !== undefined) {
+    updates.push('description = ?');
+    params.push(patch.description);
+  }
+  if (patch.metadata !== undefined) {
+    updates.push('metadata_json = ?');
+    params.push(JSON.stringify(patch.metadata));
+  }
+
+  if (updates.length > 0) {
+    params.push(campaignId);
+    db.prepare(`UPDATE campaigns SET ${updates.join(', ')} WHERE id = ?`).run(...params);
+  }
+
+  return getCampaign(campaignId)!;
+}
+
+/**
+ * Updates the campaign's metadata string as recorded on-chain.
+ * Called by the event indexer when a MetadataUpdated event is received.
+ */
+export function updateCampaignMetadata(campaignId: string, newMetadata: string): void {
+  const db = getDb();
+  const campaign = getCampaign(campaignId);
+  if (!campaign) return;
+
+  const existing = campaign.metadata ?? {};
+  const updated = { ...existing, onChainMetadata: newMetadata };
+  db.prepare(`UPDATE campaigns SET metadata_json = ? WHERE id = ?`).run(
+    JSON.stringify(updated),
+    campaignId,
+  );
+}
+
 export function getTopContributors(limit: number = 10): LeaderboardEntry[] {
   const db = getDb();
   const rows = db

backend/src/services/eventHistory.ts

@@ -1,6 +1,6 @@
 import { getDb } from './db';
 
-export type CampaignEventType = 'created' | 'pledged' | 'claimed' | 'refunded' | 'updated';
+export type CampaignEventType = 'created' | 'pledged' | 'claimed' | 'refunded' | 'updated' | 'metadata_updated';
 
 export interface BlockchainMetadata {
   txHash?: string;

backend/src/services/eventIndexer.ts

@@ -1,7 +1,7 @@
 import axios from 'axios';
 import { getDb } from './db';
 import { recordEvent, BlockchainMetadata, CampaignEventType } from './eventHistory';
-import { reconcileOnChainPledge, createCampaign, getCampaign } from './campaignStore';
+import { reconcileOnChainPledge, createCampaign, getCampaign, updateCampaignMetadata } from './campaignStore';
 import dotenv from 'dotenv';
 import { config } from '../config';
 import { logError, logInfo } from '../logger';
@@ -150,11 +150,13 @@ const TOPIC_TO_EVENT: Record<string, CampaignEventType> = {
   CampaignPledged: 'pledged',
   CampaignClaimed: 'claimed',
   CampaignRefunded: 'refunded',
+  MetadataUpdated: 'metadata_updated',
   // Alternative spellings from some contract versions
   'Goal:Create': 'created',
   'Goal:Pledge': 'pledged',
   'Goal:Claim': 'claimed',
   'Goal:Refund': 'refunded',
+  'Goal:MetaUpd': 'metadata_updated',
 };
 
 interface ParsedEvent {
@@ -247,6 +249,17 @@ function parseSorobanEvent(event: any): ParsedEvent | null {
 
 function handleParsedEvent(parsed: ParsedEvent): void {
   try {
+    if (parsed.eventType === 'metadata_updated') {
+      const newMetadata = String((parsed.metadata as any)?.new_metadata ?? '');
+      if (newMetadata && parsed.campaignId) {
+        try {
+          updateCampaignMetadata(parsed.campaignId, newMetadata);
+        } catch (err) {
+          logError(err, { event: 'soroban_metadata_update_error', campaignId: parsed.campaignId }, config.logLevel);
+        }
+      }
+    }
+
     if (parsed.eventType === 'pledged' && parsed.actor && parsed.amount != null) {
       // Check if campaign exists before reconciling
       const exists = getCampaign(parsed.campaignId);