Merge pull request #320 from DeterminateSystems/release-v3.15.2/f53e807e-112e-4841-9905-9db8f8bb04db

Release v3.15.2

Author: detsys-spaghetti[bot]

.version-determinate

@@ -1 +1 @@
-3.15.1
+3.15.2

doc/manual/source/SUMMARY.md.in

@@ -144,6 +144,7 @@
   - [Contributing](development/contributing.md)
 - [Determinate Nix Release Notes](release-notes-determinate/index.md)
   - [Changes between Nix and Determinate Nix](release-notes-determinate/changes.md)<!-- next -->
+  - [Release 3.15.2 (2026-01-20)](release-notes-determinate/v3.15.2.md)
   - [Release 3.15.1 (2025-12-24)](release-notes-determinate/v3.15.1.md)
   - [Release 3.15.0 (2025-12-19)](release-notes-determinate/v3.15.0.md)
   - [Release 3.14.0 (2025-12-08)](release-notes-determinate/v3.14.0.md)

doc/manual/source/release-notes-determinate/changes.md

@@ -1,6 +1,6 @@
 # Changes between Nix and Determinate Nix
 
-This section lists the differences between upstream Nix 2.33 and Determinate Nix 3.15.1.<!-- differences -->
+This section lists the differences between upstream Nix 2.33 and Determinate Nix 3.15.2.<!-- differences -->
 
 * In Determinate Nix, flakes are stable. You no longer need to enable the `flakes` experimental feature.
 
@@ -151,6 +151,8 @@ This section lists the differences between upstream Nix 2.33 and Determinate Nix
 
 <!-- Determinate Nix version 3.15.1 -->
 
-* Bring back the free alpha by @grahamc in [DeterminateSystems/nix-src#305](https://github.com/DeterminateSystems/nix-src/pull/305)
+<!-- Determinate Nix version 3.15.2 -->
 
-* Replace substitutable hashes with unlilkey to substitute hashes by @grahamc in [DeterminateSystems/nix-src#306](https://github.com/DeterminateSystems/nix-src/pull/306)
+* Path inputs are now lazy [DeterminateSystems/nix-src#312](https://github.com/DeterminateSystems/nix-src/pull/312)
+
+* Improved performance when fetching a lot of dependencies with curl [DeterminateSystems/nix-src#315](https://github.com/DeterminateSystems/nix-src/pull/315)

doc/manual/source/release-notes-determinate/v3.15.2.md

@@ -0,0 +1,44 @@
+# Release 3.15.2 (2026-01-20)
+
+* Based on [upstream Nix 2.33.1](../release-notes/rl-2.33.md).
+
+## What's Changed
+
+### Improved performance for users with a lot of dependencies
+
+If you even had the occasion to query your binary cache for over 110,000 store path simultaneously you might have found it rather slow.
+Previously, Nix would enqueue all the downloads at once.
+This appears to trigger quadratic behavior in curl.
+
+Determinate Nix now enqueues a reasonable number of subtitutions once.
+At the same time, we fixed a performance issue in the progress bar with so many dependencies.
+
+PR: [DeterminateSystems/nix-src#315](https://github.com/DeterminateSystems/nix-src/pull/315)
+
+### Lazy trees update: path inputs are now lazy
+
+Previously inputs like `path:///path/to/a/dependency` were eagerly fetched when lazy-trees is enabled.
+In Determinate Nix 3.15.2, path input types are also fetched lazily.
+This change saves time and improves performance for users with path inputs.
+
+PRs:
+* [DeterminateSystems/nix-src#312](https://github.com/DeterminateSystems/nix-src/pull/312)
+* [DeterminateSystems/nix-src#317](https://github.com/DeterminateSystems/nix-src/pull/317)
+
+### `nix repl` now reports the Determinate version
+
+A small change, but now `nix repl` correctly reports the Determinate Nix version:
+
+```
+$ nix repl
+Nix (Determinate Nix 3.15.1) 2.33.0
+Type :? for help.
+nix-repl>
+```
+
+PR: [DeterminateSystems/nix-src#316](https://github.com/DeterminateSystems/nix-src/pull/316)
+
+## New Contributors
+* @dliberalesso made their first contribution in [DeterminateSystems/nix-src#313](https://github.com/DeterminateSystems/nix-src/pull/313)
+
+**Full Changelog**: [v3.15.1...v3.15.2](https://github.com/DeterminateSystems/nix-src/compare/v3.15.1...v3.15.2)