Align ForestRun watchFragment with Apollo Client 3.13.9 by pavelglac · Pull Request #655 · microsoft/graphitation

pavelglac · 2026-03-26T19:02:52Z

Aligns ForestRun's watchFragment implementation with Apollo Client 3.13.9's ApolloCache.watchFragment API.

Changes Made

Observable return type: Returns Observable (from @apollo/client/utilities) instead of a custom { subscribe: ... } pattern, matching Apollo 3.13.9's API
from parameter: Accepts StoreObject | Reference | string (added Reference support)
variables option: Added generic TVars support for the variables option
Generic type parameters: Added <TData, TVars> matching Apollo's signature
Typed diffOptions: Uses Cache.DiffOptions<TData, TVars> for proper typing
Removed dataState: Removed non-standard dataState field from result to match Apollo's WatchFragmentResult
from === undefined fix: Handles undefined from gracefully to avoid calling this.identify(undefined), based on apollo-client PR #12052
ForestRun optimization integrated into watchFragment: The fragmentWatches optimization (registering watches keyed by entity ID for efficient lookups via collectAffectedWatches / transaction.affectedNodes) is now directly inside watchFragment's Observable subscriber. When optimizeFragmentReads is enabled and an entity ID is available, watchFragment computes the initial diff, delivers it via observer.next(), and registers directly in fragmentWatches. Otherwise, it falls back to watchOperation. The separate watchFragmentInternal method has been removed, eliminating unnecessary indirection.
watch() method simplified: For direct callers (e.g., QueryManager), the fragment watch registration is inlined in watch() — just accumulate/delete in fragmentWatches without immediate handling, since direct callers don't use immediate.
Added watchFragment tests: 12 new tests covering all from types (string, StoreObject, Reference), change notifications, deduplication, unsubscribe cleanup, missing data, from === undefined, both optimizeFragmentReads on/off paths, and result shape validation.

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github-actions · 2026-03-26T19:13:00Z

📊 Benchmark Analysis Report

✅ No significant performance changes detected

Threshold: 5% change

Updated: 2026-03-30T14:35:10.608Z

pavelglac · 2026-03-27T12:13:13Z

packages/apollo-forest-run/src/ForestRun.ts

+      ...otherOptions
+    } = options;
+    const query = this["getFragmentDoc"](fragment, fragmentName);
+    const id = typeof from === "string" ? from : this.identify(from);


@copilot Fix is based on this: apollographql/apollo-client#12052

Applied the same fix from that PR in commit 8e437c6. Changed the id assignment to handle from === undefined by passing it through directly instead of calling this.identify(undefined), which avoids the unwanted warning.

Agent-Logs-Url: https://github.com/microsoft/graphitation/sessions/1188cddb-5227-4dbe-8a69-1283c9aeebd2 Co-authored-by: pavelglac <42679661+pavelglac@users.noreply.github.com>

Copilot · 2026-03-27T12:16:27Z

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pavelglac · 2026-03-30T09:01:36Z

@copilot verify the implementation of watchFragment with the https://github.com/apollographql/apollo-client/blob/main/src/cache/core/cache.ts. Make ForestRun fully compatible with apollo version 3.13.9.

Agent-Logs-Url: https://github.com/microsoft/graphitation/sessions/67058345-f43e-42f4-9747-050ad6c70880 Co-authored-by: pavelglac <42679661+pavelglac@users.noreply.github.com>

Copilot · 2026-03-30T09:18:04Z

@copilot verify the implementation of watchFragment with the https://github.com/apollographql/apollo-client/blob/main/src/cache/core/cache.ts. Make ForestRun fully compatible with apol...

Verified the implementation against Apollo Client 3.13.9's ApolloCache.watchFragment and aligned it in commit 44d5137. Key changes:

Returns Observable (from @apollo/client/utilities) instead of a custom subscribe pattern
Accepts Reference type in from (matching StoreObject | Reference | string)
Supports variables option via generic TVars
Uses observer.next() inside Observable subscriber with this.watch() cleanup
Removed non-standard dataState field to match Apollo's WatchFragmentResult
Kept the from === undefined fix from apollo-client PR #12052

All 23 own tests and 114 Apollo compat tests pass.

pavelglac · 2026-03-30T10:01:43Z

@copilot Check the ForestRun integrity. Why I need watchFragmentInternal? I do not see how this can be performant. Also you are missing tests.

Agent-Logs-Url: https://github.com/microsoft/graphitation/sessions/6e241c01-f93d-4cff-a0fd-b99cd56d337a Co-authored-by: pavelglac <42679661+pavelglac@users.noreply.github.com>

Copilot · 2026-03-30T10:17:19Z

@copilot Check the ForestRun integrity. Why I need watchFragmentInternal? I do not see how this can be performant. Also you are missing tests.

Fixed in dbeb099. Two issues found and addressed:

watchFragmentInternal was missing immediate support — When optimizeFragmentReads is enabled, the public watchFragment routes through this.watch() → watchFragmentInternal, but watchFragmentInternal never handled immediate: true. This meant the Observable subscriber would never receive the initial value. Added immediate handling (matching watchOperation's pattern) so the initial diff is computed and delivered.
Added 12 tests for watchFragment covering: all from types (string, StoreObject, Reference), change notifications, deduplication, unsubscribe cleanup, missing data, from === undefined, and both optimizeFragmentReads on/off paths.

Re: why watchFragmentInternal exists — it's the existing performance optimization that stores watches keyed by entity ID (in fragmentWatches map) instead of by operation descriptor. This lets collectAffectedWatches find relevant watches directly via transaction.affectedNodes without scanning all operations. The public watchFragment (Apollo API) delegates to this.watch() which routes to this optimized path when conditions are met.

pavelglac · 2026-03-30T11:31:56Z

@copilot then i would expect this optimalization is part of the watchFragment. Refactor it to use observable and also ForestRun optimalization.

…hFragment Agent-Logs-Url: https://github.com/microsoft/graphitation/sessions/f84e3233-0a71-432d-962b-8a7f4d44a82c Co-authored-by: pavelglac <42679661+pavelglac@users.noreply.github.com>

Copilot · 2026-03-30T11:45:27Z

@copilot then i would expect this optimalization is part of the watchFragment. Refactor it to use observable and also ForestRun optimalization.

Refactored in fa6a230. watchFragmentInternal is removed — the ForestRun optimization is now directly inside watchFragment's Observable subscriber:

When optimizeFragmentReads is enabled and id is available: computes initial diff, delivers it via observer.next(), and registers directly in fragmentWatches for entity-keyed lookups
Otherwise: falls back to watchOperation

The watch() method still inlines the simple fragment registration for direct callers (QueryManager), since those don't use immediate.

All 24 own test suites (1085 tests) and 114 Apollo compat test suites (1661 tests) pass.

pavelglac added 3 commits March 26, 2026 19:02

observer

1ac160a

Change files

1a92b71

fix formatting

22650de

pavelglac commented Mar 27, 2026

View reviewed changes

Copilot started work on behalf of pavelglac March 27, 2026 12:13 View session

Fix watchFragment to handle undefined from gracefully

8e437c6

Agent-Logs-Url: https://github.com/microsoft/graphitation/sessions/1188cddb-5227-4dbe-8a69-1283c9aeebd2 Co-authored-by: pavelglac <42679661+pavelglac@users.noreply.github.com>

Copilot finished work on behalf of pavelglac March 27, 2026 12:16

Copilot started work on behalf of pavelglac March 30, 2026 09:01 View session

Align watchFragment with Apollo Client 3.13.9 ApolloCache.watchFragment

44d5137

Agent-Logs-Url: https://github.com/microsoft/graphitation/sessions/67058345-f43e-42f4-9747-050ad6c70880 Co-authored-by: pavelglac <42679661+pavelglac@users.noreply.github.com>

Copilot AI changed the title ~~observer~~ Align ForestRun watchFragment with Apollo Client 3.13.9 Mar 30, 2026

Copilot finished work on behalf of pavelglac March 30, 2026 09:21

Copilot started work on behalf of pavelglac March 30, 2026 10:01 View session

Fix watchFragmentInternal immediate mode and add watchFragment tests

dbeb099

Agent-Logs-Url: https://github.com/microsoft/graphitation/sessions/6e241c01-f93d-4cff-a0fd-b99cd56d337a Co-authored-by: pavelglac <42679661+pavelglac@users.noreply.github.com>

Copilot finished work on behalf of pavelglac March 30, 2026 10:20

Copilot started work on behalf of pavelglac March 30, 2026 11:32 View session

Refactor: merge watchFragmentInternal optimization directly into watc…

fa6a230

…hFragment Agent-Logs-Url: https://github.com/microsoft/graphitation/sessions/f84e3233-0a71-432d-962b-8a7f4d44a82c Co-authored-by: pavelglac <42679661+pavelglac@users.noreply.github.com>

Copilot finished work on behalf of pavelglac March 30, 2026 11:47

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Align ForestRun watchFragment with Apollo Client 3.13.9#655

Align ForestRun watchFragment with Apollo Client 3.13.9#655
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