fix(deepagents): merge custom middleware by name by hntrl · Pull Request #672 · langchain-ai/deepagentsjs

Hunter Lovell (hntrl) · 2026-07-13T19:54:33Z

Summary

Adds middleware override behavior to replace default middleware by .name instead of always being appended.

Changes

Add name-keyed middleware merging so custom middleware replaces matching default middleware in-place and appends novel middleware after the core stack.
Apply default-slot middleware overrides consistently when constructing main-agent and subagent middleware stacks, while preventing parent-only middleware from propagating unless it matches a subagent default slot.
Move harness tool exclusion into a private _ToolExclusionMiddleware helper so excluded tools are stripped after tool-injecting middleware has run.
Add coverage for main-agent replacement, subagent/default override propagation, parent-only middleware isolation, profile exclusions, tool-exclusion ordering, and merge precedence.

changeset-bot · 2026-07-13T19:54:38Z

🦋 Changeset detected

Latest commit: 2b1c1a4

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 3 packages

Name	Type
deepagents	Patch
deepagents-acp	Patch
@deepagents/evals	Patch

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vercel · 2026-07-13T19:54:40Z

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pkg-pr-new · 2026-07-13T19:55:45Z

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commit: 2b1c1a4

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open-swe · 2026-07-15T01:00:06Z

+  const novelMiddleware = customMiddleware.filter(
+    (middleware) => !defaultMiddlewareNames.has(middleware.name),
+  );

-  // Apply profile middleware exclusions.
+  let middleware: AgentMiddleware[] = [
+    ...mergeMiddleware(
+      coreMiddleware,
+      customMiddleware.filter((middleware) =>
+        coreMiddlewareNames.has(middleware.name),
+      ),
+    ),
+    ...novelMiddleware,


🟡 Novel duplicate middleware no longer deduplicates

This bypasses mergeMiddleware for custom names that do not match a default. As a result, middleware: [firstFoo, secondFoo] where both entries are named Foo now inserts both instances into the runtime stack, so both hooks execute. Before this split, mergeMiddleware(coreMiddleware, customMiddleware) applied the documented last-wins behavior to novel names as well. Deduplicate the novel subset by name (for example by merging it into an empty base) before spreading it into the stack.

(Refers to lines 456-467)

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@hntrl

This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## deepagents@1.11.0 ### Minor Changes - [#671](#671) [`6ae9d1e`](6ae9d1e) Thanks [@hntrl](https://github.com/hntrl)! - feat(filesystem): add allowlist for filesystem middleware tools - [#669](#669) [`4643148`](4643148) Thanks [@hntrl](https://github.com/hntrl)! - feat(deepagents): add structured system prompt configuration - [#673](#673) [`eb18c70`](eb18c70) Thanks [@hntrl](https://github.com/hntrl)! - feat(backends): add delete protocol support Adds a `DeleteResult` type and optional backend `delete` method, preserves delete through backend protocol adaptation, and implements file deletion across the built-in state, store, filesystem, composite, context hub, sandbox, and node-vfs backends. ### Patch Changes - [#691](#691) [`39a7049`](39a7049) Thanks [@colifran](https://github.com/colifran)! - fix(deepagents): backend adapter drops route prefixes - [#672](#672) [`cc26c41`](cc26c41) Thanks [@hntrl](https://github.com/hntrl)! - fix(deepagents): allow custom middleware to replace defaults by name ## deepagents-acp@0.1.19 ### Patch Changes - Updated dependencies [[`39a7049`](39a7049), [`6ae9d1e`](6ae9d1e), [`cc26c41`](cc26c41), [`4643148`](4643148), [`eb18c70`](eb18c70)]: - deepagents@1.11.0 ## @langchain/node-vfs@0.2.1 ### Patch Changes - [#673](#673) [`eb18c70`](eb18c70) Thanks [@hntrl](https://github.com/hntrl)! - feat(backends): add delete protocol support Adds a `DeleteResult` type and optional backend `delete` method, preserves delete through backend protocol adaptation, and implements file deletion across the built-in state, store, filesystem, composite, context hub, sandbox, and node-vfs backends. ## @deepagents/evals@0.0.18 ### Patch Changes - Updated dependencies [[`39a7049`](39a7049), [`6ae9d1e`](6ae9d1e), [`cc26c41`](cc26c41), [`4643148`](4643148), [`eb18c70`](eb18c70)]: - deepagents@1.11.0 Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

## Summary Adds middleware override behavior to replace default middleware by `.name` instead of always being appended. ## Changes - Add name-keyed middleware merging so custom middleware replaces matching default middleware in-place and appends novel middleware after the core stack. - Apply default-slot middleware overrides consistently when constructing main-agent and subagent middleware stacks, while preventing parent-only middleware from propagating unless it matches a subagent default slot. - Move harness tool exclusion into a private `_ToolExclusionMiddleware` helper so excluded tools are stripped after tool-injecting middleware has run. - Add coverage for main-agent replacement, subagent/default override propagation, parent-only middleware isolation, profile exclusions, tool-exclusion ordering, and merge precedence.

@hntrl

This PR was opened by the [Changesets release](https://github.com/changesets/action) GitHub action. When you're ready to do a release, you can merge this and the packages will be published to npm automatically. If you're not ready to do a release yet, that's fine, whenever you add more changesets to main, this PR will be updated. # Releases ## deepagents@1.11.0 ### Minor Changes - [#671](#671) [`6ae9d1e`](6ae9d1e) Thanks [@hntrl](https://github.com/hntrl)! - feat(filesystem): add allowlist for filesystem middleware tools - [#669](#669) [`4643148`](4643148) Thanks [@hntrl](https://github.com/hntrl)! - feat(deepagents): add structured system prompt configuration - [#673](#673) [`eb18c70`](eb18c70) Thanks [@hntrl](https://github.com/hntrl)! - feat(backends): add delete protocol support Adds a `DeleteResult` type and optional backend `delete` method, preserves delete through backend protocol adaptation, and implements file deletion across the built-in state, store, filesystem, composite, context hub, sandbox, and node-vfs backends. ### Patch Changes - [#691](#691) [`39a7049`](39a7049) Thanks [@colifran](https://github.com/colifran)! - fix(deepagents): backend adapter drops route prefixes - [#672](#672) [`cc26c41`](cc26c41) Thanks [@hntrl](https://github.com/hntrl)! - fix(deepagents): allow custom middleware to replace defaults by name ## deepagents-acp@0.1.19 ### Patch Changes - Updated dependencies [[`39a7049`](39a7049), [`6ae9d1e`](6ae9d1e), [`cc26c41`](cc26c41), [`4643148`](4643148), [`eb18c70`](eb18c70)]: - deepagents@1.11.0 ## @langchain/node-vfs@0.2.1 ### Patch Changes - [#673](#673) [`eb18c70`](eb18c70) Thanks [@hntrl](https://github.com/hntrl)! - feat(backends): add delete protocol support Adds a `DeleteResult` type and optional backend `delete` method, preserves delete through backend protocol adaptation, and implements file deletion across the built-in state, store, filesystem, composite, context hub, sandbox, and node-vfs backends. ## @deepagents/evals@0.0.18 ### Patch Changes - Updated dependencies [[`39a7049`](39a7049), [`6ae9d1e`](6ae9d1e), [`cc26c41`](cc26c41), [`4643148`](4643148), [`eb18c70`](eb18c70)]: - deepagents@1.11.0 Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

fix(deepagents): merge custom middleware by name

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open-swe Bot reviewed Jul 13, 2026

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LangChain (langchain-ai) deleted a comment from open-swe Bot Jul 13, 2026

fix(deepagents): limit inherited middleware overrides to gp

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refactor(deepagents): pass gp overrides through spec

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refactor(deepagents): derive gp middleware override names

a16285f

vercel Bot deployed to Preview July 15, 2026 00:36 View deployment

refactor(deepagents): reuse normalized gp middleware

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open-swe Bot reviewed Jul 15, 2026

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Comment thread libs/deepagents/src/agent.ts Outdated

fix(deepagents): replace tail middleware by name

04053f4

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open-swe Bot reviewed Jul 15, 2026

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refactor(deepagents): clarify middleware replacement assembly

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refactor(deepagents): consolidate middleware stack merging

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refactor(deepagents): move middleware merge helpers

2b1c1a4

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Hunter Lovell (hntrl) merged commit cc26c41 into main Jul 15, 2026
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Hunter Lovell (hntrl) deleted the hunter/middleware-merge-values branch July 15, 2026 02:08

github-actions Bot mentioned this pull request Jul 15, 2026

chore: version packages #676

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fix(deepagents): merge custom middleware by name - #672

fix(deepagents): merge custom middleware by name#672
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Hunter Lovell (hntrl) commented Jul 13, 2026

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