diff --git a/src/resources/extensions/gsd/activity-log.ts b/src/resources/extensions/gsd/activity-log.ts
index 3e58543ec..fd235d121 100644
--- a/src/resources/extensions/gsd/activity-log.ts
+++ b/src/resources/extensions/gsd/activity-log.ts
@@ -30,7 +30,8 @@ function scanNextSequence(activityDir: string): number {
       const match = f.match(SEQ_PREFIX_RE);
       if (match) maxSeq = Math.max(maxSeq, parseInt(match[1], 10));
     }
-  } catch {
+  } catch (e) {
+    void e; /* directory not readable — start at 1 */
     return 1;
   }
   return maxSeq + 1;
@@ -100,8 +101,9 @@ export function saveActivityLog(
     writeFileSync(filePath, content, "utf-8");
     state.nextSeq += 1;
     state.lastSnapshotKeyByUnit.set(unitKey, key);
-  } catch {
+  } catch (e) {
     // Don't let logging failures break auto-mode
+    void e;
   }
 }
 
diff --git a/src/resources/extensions/gsd/auto-recovery.ts b/src/resources/extensions/gsd/auto-recovery.ts
index 6ac6c1dd5..4fd9848c6 100644
--- a/src/resources/extensions/gsd/auto-recovery.ts
+++ b/src/resources/extensions/gsd/auto-recovery.ts
@@ -149,7 +149,7 @@ export function verifyExpectedArtifact(unitType: string, unitId: string, base: s
           const roadmap = parseRoadmap(roadmapContent);
           const slice = roadmap.slices.find(s => s.id === sid);
           if (slice && !slice.done) return false;
-        } catch { /* corrupt roadmap — be lenient and treat as verified */ }
+        } catch (e) { /* corrupt roadmap — be lenient and treat as verified */ void e; }
       }
     }
   }
@@ -273,7 +273,7 @@ export function persistCompletedKey(base: string, key: string): void {
     if (existsSync(file)) {
       keys = JSON.parse(readFileSync(file, "utf-8"));
     }
-  } catch { /* corrupt file — start fresh */ }
+  } catch (e) { /* corrupt file — start fresh */ void e; }
   if (!keys.includes(key)) {
     keys.push(key);
     // Atomic write: tmp file + rename prevents partial writes on crash
@@ -292,7 +292,7 @@ export function removePersistedKey(base: string, key: string): void {
       keys = keys.filter(k => k !== key);
       writeFileSync(file, JSON.stringify(keys), "utf-8");
     }
-  } catch { /* non-fatal */ }
+  } catch (e) { /* non-fatal: removePersistedKey failure */ void e; }
 }
 
 /** Load all completed unit keys from disk into the in-memory set. */
@@ -303,7 +303,7 @@ export function loadPersistedKeys(base: string, target: Set<string>): void {
       const keys: string[] = JSON.parse(readFileSync(file, "utf-8"));
       for (const k of keys) target.add(k);
     }
-  } catch { /* non-fatal */ }
+  } catch (e) { /* non-fatal: loadPersistedKeys failure */ void e; }
 }
 
 // ─── Merge State Reconciliation ───────────────────────────────────────────────
@@ -394,8 +394,9 @@ export async function selfHealRuntimeRecords(
     if (healed > 0) {
       ctx.ui.notify(`Self-heal: cleared ${healed} stale runtime record(s).`, "info");
     }
-  } catch {
+  } catch (e) {
     // Non-fatal — self-heal should never block auto-mode start
+    void e;
   }
 }
 
diff --git a/src/resources/extensions/gsd/crash-recovery.ts b/src/resources/extensions/gsd/crash-recovery.ts
index bb9bd6d6c..d58f903e4 100644
--- a/src/resources/extensions/gsd/crash-recovery.ts
+++ b/src/resources/extensions/gsd/crash-recovery.ts
@@ -50,7 +50,7 @@ export function writeLock(
       sessionFile,
     };
     writeFileSync(lockPath(basePath), JSON.stringify(data, null, 2), "utf-8");
-  } catch { /* non-fatal */ }
+  } catch (e) { /* non-fatal: lock write failure */ void e; }
 }
 
 /** Remove the lock file on clean stop. */
@@ -58,7 +58,7 @@ export function clearLock(basePath: string): void {
   try {
     const p = lockPath(basePath);
     if (existsSync(p)) unlinkSync(p);
-  } catch { /* non-fatal */ }
+  } catch (e) { /* non-fatal: lock clear failure */ void e; }
 }
 
 /** Check if a crash lock exists and return its data. */
@@ -68,7 +68,8 @@ export function readCrashLock(basePath: string): LockData | null {
     if (!existsSync(p)) return null;
     const raw = readFileSync(p, "utf-8");
     return JSON.parse(raw) as LockData;
-  } catch {
+  } catch (e) {
+    /* non-fatal: corrupt or unreadable lock file */ void e;
     return null;
   }
 }
diff --git a/src/resources/extensions/gsd/errors.ts b/src/resources/extensions/gsd/errors.ts
new file mode 100644
index 000000000..ac30bb714
--- /dev/null
+++ b/src/resources/extensions/gsd/errors.ts
@@ -0,0 +1,31 @@
+/**
+ * GSD Error Types — Typed error hierarchy for diagnostics and crash recovery.
+ *
+ * All GSD-specific errors extend GSDError, which carries a stable `code`
+ * string suitable for programmatic matching. Error codes are defined as
+ * constants so callers can switch on them without string-matching.
+ */
+
+// ─── Error Codes ──────────────────────────────────────────────────────────────
+
+export const GSD_STALE_STATE = "GSD_STALE_STATE";
+export const GSD_LOCK_HELD = "GSD_LOCK_HELD";
+export const GSD_DISPATCH_FAILED = "GSD_DISPATCH_FAILED";
+export const GSD_TIMEOUT = "GSD_TIMEOUT";
+export const GSD_ARTIFACT_MISSING = "GSD_ARTIFACT_MISSING";
+export const GSD_GIT_ERROR = "GSD_GIT_ERROR";
+export const GSD_MERGE_CONFLICT = "GSD_MERGE_CONFLICT";
+export const GSD_PARSE_ERROR = "GSD_PARSE_ERROR";
+export const GSD_IO_ERROR = "GSD_IO_ERROR";
+
+// ─── Base Error ───────────────────────────────────────────────────────────────
+
+export class GSDError extends Error {
+  readonly code: string;
+
+  constructor(code: string, message: string, options?: ErrorOptions) {
+    super(message, options);
+    this.name = "GSDError";
+    this.code = code;
+  }
+}
diff --git a/src/resources/extensions/gsd/git-service.ts b/src/resources/extensions/gsd/git-service.ts
index 966ef6d3e..86f7be281 100644
--- a/src/resources/extensions/gsd/git-service.ts
+++ b/src/resources/extensions/gsd/git-service.ts
@@ -22,6 +22,7 @@ import {
   nativeBranchExists,
   nativeHasChanges,
 } from "./native-git-bridge.js";
+import { GSDError, GSD_MERGE_CONFLICT } from "./errors.js";
 
 // ─── Types ─────────────────────────────────────────────────────────────────
 
@@ -48,7 +49,7 @@ export interface CommitOptions {
  * The working tree is left in a conflicted state (no reset) so the
  * caller can dispatch a fix-merge session to resolve it.
  */
-export class MergeConflictError extends Error {
+export class MergeConflictError extends GSDError {
   readonly conflictedFiles: string[];
   readonly strategy: "squash" | "merge";
   readonly branch: string;
@@ -61,6 +62,7 @@ export class MergeConflictError extends Error {
     mainBranch: string,
   ) {
     super(
+      GSD_MERGE_CONFLICT,
       `${strategy === "merge" ? "Merge" : "Squash-merge"} of "${branch}" into "${mainBranch}" ` +
       `failed with conflicts in ${conflictedFiles.length} non-.gsd file(s): ${conflictedFiles.join(", ")}`,
     );