feat(agent-builder): raise prompt-hint clamp to 350 (#1139)

Raise the client-side clamp (maxHintLength) from 240 to 350 so hints up
to the new backend cap aren't truncated in the composer. Clamp test now
feeds a 400-char hint and asserts 350.


Claude-Session: https://claude.ai/code/session_01Jp2NeQiZiBavQCgyPZVZKd

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: saulmc

Convos/Agent Builder/PromptHintsModel.swift

@@ -104,7 +104,7 @@ final class PromptHintsModel {
         }
     }
 
-    /// Trim, drop empties, and clamp each hint to the backend's 240-char
+    /// Trim, drop empties, and clamp each hint to the backend's 350-char
     /// contract so a malformed row can't blow out the composer.
     private static func sanitize(_ raw: [String]) -> [String] {
         raw
@@ -117,6 +117,6 @@ final class PromptHintsModel {
 
     private enum Constant {
         static let maxAttempts: Int = 5
-        static let maxHintLength: Int = 240
+        static let maxHintLength: Int = 350
     }
 }

ConvosCore/Sources/ConvosCore/API/ConvosAPIClient+Models.swift

@@ -341,7 +341,7 @@ public enum ConvosAPI {
     }
 
     /// Response envelope for `GET /v2/agent-prompt-hints` -- a flat list of
-    /// curated prompt strings (each <= 240 chars) the agent builder's dice
+    /// curated prompt strings (each <= 350 chars) the agent builder's dice
     /// control drops into the "What needs done?" composer. Public and
     /// unauthenticated; decoding is tolerant of extra keys via default Codable
     /// behavior.

ConvosTests/PromptHintsModelTests.swift

@@ -65,13 +65,13 @@ final class PromptHintsModelTests: XCTestCase {
     }
 
     func testSanitizeTrimsDropsEmptyAndClamps() async {
-        let long = String(repeating: "x", count: 300)
+        let long = String(repeating: "x", count: 400)
         let disk = DiskSpy(stored: [])
         let model = makeModel(service: MockPromptHintsService(hints: ["  spaced  ", "", long]), disk: disk)
         await model.loadOnLaunch()
         XCTAssertEqual(model.hints.count, 2, "Empty / whitespace-only hints are dropped")
         XCTAssertEqual(model.hints.first, "spaced", "Hints are trimmed")
-        XCTAssertEqual(model.hints.last?.count, 240, "Hints are clamped to the 240-char contract")
+        XCTAssertEqual(model.hints.last?.count, 350, "Hints are clamped to the 350-char contract")
     }
 
     func testLoadOnLaunchRunsOnlyOnce() async {