From 80ec0791eb43366ef126dd7150896bd70ad3c785 Mon Sep 17 00:00:00 2001
From: Tom Boucher <trekkie@nomorestars.com>
Date: Fri, 7 Aug 2026 06:16:22 -0400
Subject: [PATCH] fix(#3052): preserve frontmatter last_activity_desc on
 same-date body prose conflict (#3140)

* fix(#3052): preserve frontmatter last_activity_desc on same-date body prose conflict

preferNewerLastActivity only preserved last_activity_desc when the derived
date was OLDER than the existing frontmatter date. When the dates matched
(same-date), the derived body prose (potentially stale) overwrote the
authoritative frontmatter desc.

Fix: when derDate === exDate, also preserve the frontmatter desc.

* chore(#3052): backfill changeset PR number 3140

---------

Co-authored-by: sim <sim@local>
---
 .changeset/rapid-sloths-romp.md |  5 +++
 src/state.cts                   |  7 ++++
 tests/state.test.cjs            | 57 +++++++++++++++++++++++++++++++++
 3 files changed, 69 insertions(+)
 create mode 100644 .changeset/rapid-sloths-romp.md

diff --git a/.changeset/rapid-sloths-romp.md b/.changeset/rapid-sloths-romp.md
new file mode 100644
index 000000000..a929b46db
--- /dev/null
+++ b/.changeset/rapid-sloths-romp.md
@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 3140
+---
+**`state planned-phase` no longer overwrites authoritative `last_activity_desc`** — when the frontmatter and body had the same activity date but different descriptions, the write path preserved the date but overwrote the frontmatter's description with stale body prose. Same-date frontmatter desc is now preserved. (#3052)
diff --git a/src/state.cts b/src/state.cts
index 0d4561b6b..b8e84bb3d 100644
--- a/src/state.cts
+++ b/src/state.cts
@@ -1392,6 +1392,13 @@ function preferNewerLastActivity(
     if (existingFm['last_activity_desc'] !== undefined) {
       derivedFm['last_activity_desc'] = existingFm['last_activity_desc'];
     }
+  } else if (derDate === exDate) {
+    // #3052: same-date — frontmatter is authoritative for this date, so
+    // preserve its last_activity_desc rather than letting the derived body
+    // prose (which may be stale) overwrite it.
+    if (existingFm['last_activity_desc'] !== undefined) {
+      derivedFm['last_activity_desc'] = existingFm['last_activity_desc'];
+    }
   }
 }
 
diff --git a/tests/state.test.cjs b/tests/state.test.cjs
index cb7edb15a..7def31cf7 100644
--- a/tests/state.test.cjs
+++ b/tests/state.test.cjs
@@ -2895,6 +2895,63 @@ describe('state planned-phase command', () => {
   });
 });
 
+// ─────────────────────────────────────────────────────────────────────────────
+// #3052: state planned-phase must not overwrite authoritative same-date
+// last_activity_desc from stale body prose
+// ─────────────────────────────────────────────────────────────────────────────
+
+describe('#3052: planned-phase preserves same-date last_activity_desc', () => {
+  let tmpDir;
+
+  beforeEach(() => {
+    tmpDir = createFixture();
+  });
+
+  afterEach(() => {
+    cleanup(tmpDir);
+  });
+
+  test('same-date conflicting desc: frontmatter desc is preserved', () => {
+    // Frontmatter has authoritative desc; body has stale desc for the SAME date
+    fs.writeFileSync(
+      path.join(tmpDir, '.planning', 'STATE.md'),
+      [
+        '---',
+        'last_activity: 2020-09-10',
+        'last_activity_desc: authoritative description',
+        '---',
+        '',
+        '# Project State',
+        '',
+        '**Status:** Planning',
+        '**Last Activity:** 2020-09-10 — stale description',
+        '**Current Phase:** 1',
+        '',
+      ].join('\n'),
+    );
+
+    const result = runGsdTools(
+      ['state', 'planned-phase', '--phase', '1', '--plans', '3'],
+      tmpDir,
+      { GSD_NOW_MS: String(Date.parse('2020-09-10T15:00:00.000Z')) },
+    );
+    assert.ok(result.success, `Command failed: ${result.error}`);
+
+    const stateContent = fs.readFileSync(path.join(tmpDir, '.planning', 'STATE.md'), 'utf-8');
+    // Extract only the frontmatter (between --- fences) to check the desc
+    const fmMatch = stateContent.match(/^---\r?\n([\s\S]*?)\r?\n---/);
+    const frontmatter = fmMatch ? fmMatch[1] : '';
+    assert.ok(
+      frontmatter.includes('authoritative description'),
+      'frontmatter last_activity_desc must be preserved when same-date body prose conflicts',
+    );
+    assert.ok(
+      !frontmatter.includes('stale description'),
+      'stale body desc must NOT appear in frontmatter (it may remain in body prose)',
+    );
+  });
+});
+
 // ─────────────────────────────────────────────────────────────────────────────
 // bug #1070 regression: "Complete ✓" terminal status must yield to planned-phase
 // ─────────────────────────────────────────────────────────────────────────────