From 54ce2a230f9ef7bbd47edb5e2e6fb85106a7b1b3 Mon Sep 17 00:00:00 2001
From: Vui-Chee <vuicheesiew@gmail.com>
Date: Sat, 7 Mar 2026 15:20:49 +0800
Subject: [PATCH] indexer: handle missing parent objects in shallow clones and
 root commits

When `semcode-index --source` is run without `--git`, it auto-detects
HEAD and constructs the range `HEAD^..HEAD`. On a shallow clone or a
repo initialized from a tarball (single root commit), `HEAD^` refers to
a parent object that doesn't exist in the local object store, causing
gix to error with "An object with id ... could not be found".

Fix `list_shas_in_range` to catch this error and fall back to returning
just the target commit SHA, so indexing proceeds normally with the
single HEAD commit.

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>
---
 src/indexer.rs | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/src/indexer.rs b/src/indexer.rs
index 58675bd..3983059 100644
--- a/src/indexer.rs
+++ b/src/indexer.rs
@@ -116,12 +116,24 @@ pub fn list_shas_in_range(repo: &gix::Repository, range: &str) -> Result<Vec<Str
             .all()?
     } else {
         // Exclude commits reachable from from_spec
-        let from_commit = resolve_to_commit(repo, from_spec)?;
-        let from_id = from_commit.id().detach();
-        repo.rev_walk([to_id])
-            .with_hidden([from_id])
-            .sorting(Sorting::ByCommitTime(Default::default()))
-            .all()?
+        match resolve_to_commit(repo, from_spec) {
+            Ok(from_commit) => {
+                let from_id = from_commit.id().detach();
+                repo.rev_walk([to_id])
+                    .with_hidden([from_id])
+                    .sorting(Sorting::ByCommitTime(Default::default()))
+                    .all()?
+            }
+            Err(e) => {
+                // Parent commit not found in local object store (shallow clone or root commit).
+                // Fall back to returning just the single target commit.
+                info!(
+                    "Could not resolve '{}' ({}); falling back to single-commit indexing",
+                    from_spec, e
+                );
+                return Ok(vec![to_id.to_string()]);
+            }
+        }
     };
 
     let mut shas = Vec::new();