refactor(mobile): give the one-key unchecked reader a name

Four readers were the same three lines: read one property off the reply, wrap
it unchecked. `rpcUncheckedMemberReader` is the one-key sibling of the existing
`rpcUncheckedPayloadReader`, so the annotation and the closure go away at each
site. The pilot's `commitCompareEntriesReader` is converted too, so the helper
has no longhand twin left to copy from.

No behaviour change: the helper composes the same `rpcReadUnchecked` over
`rpcPayloadMember`, including the property-read exception on a null result.

Claude-Session: https://claude.ai/code/session_01JNnE9qzUZMMnqpZWCqM3nb

mobile/src/source-control/mobile-git-read-operations.ts

@@ -1,6 +1,9 @@
 import { bindDeferredRpcOperation, defineRpcOperation } from '../transport/rpc-operation'
 import type { RpcCompatibleReader } from '../transport/rpc-operation-contract'
-import { rpcPayloadMember, rpcUncheckedPayloadReader } from '../transport/rpc-reader-payload'
+import {
+  rpcUncheckedMemberReader,
+  rpcUncheckedPayloadReader
+} from '../transport/rpc-reader-payload'
 import { readMobileGitStatusResult } from '../session/mobile-diff-review-rpc'
 import type { MobileGitStatusResult } from './mobile-git-status'
 
@@ -58,27 +61,18 @@ export const gitHistoryRead = bindDeferredRpcOperation(
   })
 )
 
-const commitCompareEntriesReader: RpcCompatibleReader<
-  unknown,
-  'commit-compare-entries',
-  unknown
-> = (raw) => ({
-  compatible: true,
-  variant: 'commit-compare-entries',
-  // Keeps the property-read exception the expanded-commit list already relies on: a null result
-  // throws inside the load, which is what leaves an already-loaded file list alone.
-  value: rpcPayloadMember(raw, 'entries'),
-  salvage: { droppedPaths: [], droppedCount: 0 }
-})
-
-/** A refused compare leaves the row's file list untouched, so refusal is a skip, not a throw. */
+/**
+ * A refused compare leaves the row's file list untouched, so refusal is a skip, not a throw. The
+ * member read keeps the property-read exception a null result throws, which is what leaves an
+ * already-loaded file list alone.
+ */
 export const gitCommitCompareRead = bindDeferredRpcOperation(
   defineRpcOperation({
     name: 'git.commit-compare-entries-or-skip',
     method: 'git.commitCompare',
     acceptance: 'success-result-or-skip',
     barrier: 'after-caller-barrier',
-    read: commitCompareEntriesReader
+    read: rpcUncheckedMemberReader('commit-compare-entries', 'entries')
   })
 )
 

mobile/src/tasks/mobile-task-runtime-operations.ts

@@ -1,8 +1,6 @@
 import { bindDeferredRpcOperation, defineRpcOperation } from '../transport/rpc-operation'
-import type { RpcCompatibleReader } from '../transport/rpc-operation-contract'
 import {
-  rpcPayloadMember,
-  rpcReadUnchecked,
+  rpcUncheckedMemberReader,
   rpcUncheckedPayloadReader
 } from '../transport/rpc-reader-payload'
 
@@ -23,9 +21,6 @@ export const taskRuntimeStatusRead = bindDeferredRpcOperation(
   })
 )
 
-const persistedUiStateReader: RpcCompatibleReader<unknown, 'ui-state-member', unknown> = (raw) =>
-  rpcReadUnchecked('ui-state-member', rpcPayloadMember(raw, 'ui'))
-
 /**
  * Persisted UI state, read at the hydration barrier alongside preflight and Linear status. A
  * refused read leaves the screen on its defaults rather than failing hydration, so it is a skip.
@@ -36,7 +31,7 @@ export const taskUiStateRead = bindDeferredRpcOperation(
     method: 'ui.get',
     acceptance: 'success-result-or-skip',
     barrier: 'after-caller-barrier',
-    read: persistedUiStateReader
+    read: rpcUncheckedMemberReader('ui-state-member', 'ui')
   })
 )
 

mobile/src/tasks/mobile-workspace-source-operations.ts

@@ -1,17 +1,13 @@
 import { bindDeferredRpcOperation, defineRpcOperation } from '../transport/rpc-operation'
-import type { RpcCompatibleReader } from '../transport/rpc-operation-contract'
 import {
-  rpcPayloadMember,
-  rpcReadUnchecked,
+  rpcUncheckedMemberReader,
   rpcUncheckedPayloadReader
 } from '../transport/rpc-reader-payload'
 
 // The repo and SSH reads the workspace-create drawer runs: connection state, agent detection,
 // repo-owned setup hooks, sparse presets and base-branch search.
 
-const sshConnectionStateReader: RpcCompatibleReader<unknown, 'ssh-connection-state', unknown> = (
-  raw
-) => rpcReadUnchecked('ssh-connection-state', rpcPayloadMember(raw, 'state'))
+const sshConnectionStateReader = rpcUncheckedMemberReader('ssh-connection-state', 'state')
 
 /** Connecting an SSH repo before create. The reply's only read field is `state`. */
 export const sshRepoConnectRun = bindDeferredRpcOperation(
@@ -69,30 +65,23 @@ export const repoSetupHooksRead = bindDeferredRpcOperation(
   })
 )
 
-const sparsePresetListReader: RpcCompatibleReader<unknown, 'sparse-presets', unknown> = (raw) =>
-  rpcReadUnchecked('sparse-presets', rpcPayloadMember(raw, 'presets'))
-
 export const repoSparsePresetListRead = bindDeferredRpcOperation(
   defineRpcOperation({
     name: 'repo.sparse-preset-list',
     method: 'repo.sparsePresets',
     acceptance: 'require-result-or-throw-message',
     barrier: 'after-caller-barrier',
-    read: sparsePresetListReader
+    read: rpcUncheckedMemberReader('sparse-presets', 'presets')
   })
 )
 
-const savedSparsePresetReader: RpcCompatibleReader<unknown, 'saved-sparse-preset', unknown> = (
-  raw
-) => rpcReadUnchecked('saved-sparse-preset', rpcPayloadMember(raw, 'preset'))
-
 export const repoSparsePresetSaveRun = bindDeferredRpcOperation(
   defineRpcOperation({
     name: 'repo.save-sparse-preset',
     method: 'repo.saveSparsePreset',
     acceptance: 'require-result-or-throw-message',
     barrier: 'after-caller-barrier',
-    read: savedSparsePresetReader
+    read: rpcUncheckedMemberReader('saved-sparse-preset', 'preset')
   })
 )
 

mobile/src/transport/rpc-reader-payload.ts

@@ -25,3 +25,11 @@ export function rpcUncheckedPayloadReader<Variant extends string>(
 ): RpcCompatibleReader<unknown, Variant, unknown> {
   return (raw) => rpcReadUnchecked(variant, raw)
 }
+
+/** One property off the payload, unchecked. The shape for a call site that cast `result.field`. */
+export function rpcUncheckedMemberReader<Variant extends string>(
+  variant: Variant,
+  key: string
+): RpcCompatibleReader<unknown, Variant, unknown> {
+  return (raw) => rpcReadUnchecked(variant, rpcPayloadMember(raw, key))
+}