fix(cache): don't infer input reads when input auto is disabled

When `output_config.includes_auto` is true (the default), fspy is
enabled for write tracking. Previously this caused fspy reads to flow
into `PostRunFingerprint` even if the user set `input: []` or an
explicit-only list, silently re-introducing inferred input dependencies
and causing spurious cache misses from unrelated reads.

Gate `inferred_reads` on `input_config.includes_auto`: when false, pass
an empty map to the fingerprint and overlap check, while still keeping
fspy writes available for output archiving. Adds an e2e test
`explicit_input_ignores_fspy_reads` to cover this. Also updates three
`input_cache_test` snapshots that were capturing the bug as expected
behaviour (cache miss on unrelated file change) — they now correctly
reflect cache hits.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: branchseer

crates/vite_task/src/session/execute/mod.rs

@@ -572,13 +572,14 @@ pub async fn execute_spawn(
                 .as_ref()
                 .map(|raw| TrackedPathAccesses::from_raw(raw, cache_base_path));
 
-            // Inferred input reads: filter path_reads by input negatives.
-            // Separate from write filtering (which uses output negatives inside
-            // `collect_and_archive_outputs`) so users can set `!dist/**` on
-            // input without accidentally dropping writes to `dist`.
+            // Inferred input reads: gated by `input_config.includes_auto` and
+            // filtered by input negatives. When input auto is disabled, no reads
+            // contribute to the fingerprint even if fspy was enabled for output
+            // tracking.
             let empty_reads = HashMap::default();
             let inferred_reads: HashMap<RelativePathBuf, tracked_accesses::PathRead> =
-                if let Some(pa) = path_accesses.as_ref()
+                if metadata.input_config.includes_auto
+                    && let Some(pa) = path_accesses.as_ref()
                     && let Some(negatives) = fspy_input_negatives.as_deref()
                 {
                     pa.path_reads

crates/vite_task_bin/tests/e2e_snapshots/fixtures/input_cache_test/snapshots/empty_input___hit_despite_file_changes.md

@@ -18,6 +18,9 @@ export const main = 'initial';
 ## `vt run empty-inputs`
 
 ```
-$ vtt print-file ./src/main.ts ○ cache miss: 'src/main.ts' modified, executing
-export const main = 'modified';
+$ vtt print-file ./src/main.ts ◉ cache hit, replaying
+export const main = 'initial';
+
+---
+vt run: cache hit.
 ```

crates/vite_task_bin/tests/e2e_snapshots/fixtures/input_cache_test/snapshots/folder_input___hit_despite_file_changes_and_folder_deletion.md

@@ -18,8 +18,11 @@ export const main = 'initial';
 ## `vt run folder-input`
 
 ```
-$ vtt print-file src/main.ts ○ cache miss: 'src/main.ts' modified, executing
-export const main = 'modified';
+$ vtt print-file src/main.ts ◉ cache hit, replaying
+export const main = 'initial';
+
+---
+vt run: cache hit.
 ```
 
 ## `vtt rm -rf src`
@@ -30,6 +33,9 @@ export const main = 'modified';
 ## `vt run folder-input`
 
 ```
-$ vtt print-file src/main.ts ○ cache miss: 'main.ts' removed from 'src', executing
-src/main.ts: not found
+$ vtt print-file src/main.ts ◉ cache hit, replaying
+export const main = 'initial';
+
+---
+vt run: cache hit.
 ```

crates/vite_task_bin/tests/e2e_snapshots/fixtures/input_cache_test/snapshots/positive_globs___hit_on_read_but_unmatched_file.md

@@ -19,7 +19,10 @@ export const utils = 'initial';
 ## `vt run positive-globs-reads-unmatched`
 
 ```
-$ vtt print-file src/main.ts src/utils.ts ○ cache miss: 'src/utils.ts' modified, executing
+$ vtt print-file src/main.ts src/utils.ts ◉ cache hit, replaying
 export const main = 'initial';
-export const utils = 'modified';
+export const utils = 'initial';
+
+---
+vt run: cache hit.
 ```

crates/vite_task_bin/tests/e2e_snapshots/fixtures/output_cache_test/README.md

@@ -0,0 +1 @@
+v1

crates/vite_task_bin/tests/e2e_snapshots/fixtures/output_cache_test/snapshots.toml

@@ -129,3 +129,29 @@ steps = [
   ["vtt", "print-file", "dist/out.txt"],
 ]
 
+# 7. When input auto is disabled (explicit globs only), unrelated reads tracked
+# by fspy must NOT become inferred inputs. Default auto output still needs fspy
+# for write tracking, but reads outside `input: ["src/**"]` should be ignored.
+[[e2e]]
+name = "explicit_input_ignores_fspy_reads"
+steps = [
+  [
+    "vt",
+    "run",
+    "explicit-input-auto-output",
+  ],
+  # Modify README.md (read by the task, NOT in input globs)
+  [
+    "vtt",
+    "replace-file-content",
+    "README.md",
+    "v1",
+    "v2",
+  ],
+  # Should be a cache hit: README.md is not an input
+  { argv = [
+    "vt",
+    "run",
+    "explicit-input-auto-output",
+  ], comment = "cache hit: README.md not in input globs" },
+]

crates/vite_task_bin/tests/e2e_snapshots/fixtures/output_cache_test/snapshots/explicit_input_ignores_fspy_reads.md

@@ -0,0 +1,38 @@
+# explicit_input_ignores_fspy_reads
+
+## `vt run explicit-input-auto-output`
+
+```
+$ vtt print-file README.md
+v1
+
+$ vtt write-file dist/out.txt built
+
+$ vtt print done
+done
+
+---
+vt run: 0/3 cache hit (0%). (Run `vt run --last-details` for full details)
+```
+
+## `vtt replace-file-content README.md v1 v2`
+
+```
+```
+
+## `vt run explicit-input-auto-output`
+
+cache hit: README.md not in input globs
+
+```
+$ vtt print-file README.md ◉ cache hit, replaying
+v1
+
+$ vtt write-file dist/out.txt built ◉ cache hit, replaying
+
+$ vtt print done ◉ cache hit, replaying
+done
+
+---
+vt run: 3/3 cache hit (100%). (Run `vt run --last-details` for full details)
+```

crates/vite_task_bin/tests/e2e_snapshots/fixtures/output_cache_test/vite-task.json

@@ -28,6 +28,11 @@
       "command": "vtt write-file dist/out.txt built && vtt print done",
       "input": [{ "auto": true }, "!dist/**"],
       "cache": true
+    },
+    "explicit-input-auto-output": {
+      "command": "vtt print-file README.md && vtt write-file dist/out.txt built && vtt print done",
+      "input": ["src/**"],
+      "cache": true
     }
   }
 }