fix: pass verificationBudget to execute-task prompt template

buildExecuteTaskPrompt() was missing the verificationBudget variable
that the execute-task.md template expects. The prompt-loader's strict
placeholder validator threw on every auto-mode task dispatch, blocking
all execution entirely.

Compute the budget from the executor's context window using the existing
computeBudgets() engine and pass it as ~NNK chars format string.

Fixes #707

src/resources/extensions/gsd/auto-prompts.ts

@@ -716,6 +716,12 @@ export async function buildExecuteTaskPrompt(
   const activeOverrides = await loadActiveOverrides(base);
   const overridesSection = formatOverridesSection(activeOverrides);
 
+  // Compute verification budget for the executor's context window (issue #707)
+  const prefs = loadEffectiveGSDPreferences();
+  const contextWindow = resolveExecutorContextWindow(undefined, prefs?.preferences);
+  const budgets = computeBudgets(contextWindow);
+  const verificationBudget = `~${Math.round(budgets.verificationBudgetChars / 1000)}K chars`;
+
   return loadPrompt("execute-task", {
     overridesSection,
     workingDirectory: base,
@@ -730,6 +736,7 @@ export async function buildExecuteTaskPrompt(
     priorTaskLines: priorLines,
     taskSummaryPath,
     inlinedTemplates,
+    verificationBudget,
   });
 }
 

src/resources/extensions/gsd/tests/context-compression.test.ts

@@ -74,6 +74,19 @@ test("compression: buildExecuteTaskPrompt minimal truncates prior summaries", ()
   );
 });
 
+test("compression: buildExecuteTaskPrompt passes verificationBudget to loadPrompt (#707)", () => {
+  // The execute-task template declares {{verificationBudget}} — the builder must supply it
+  assert.ok(
+    promptsSrc.includes("verificationBudget"),
+    "buildExecuteTaskPrompt should pass verificationBudget in the loadPrompt vars object",
+  );
+  // Verify it computes the budget from computeBudgets
+  assert.ok(
+    promptsSrc.includes("computeBudgets(contextWindow)"),
+    "buildExecuteTaskPrompt should compute budgets from the executor context window",
+  );
+});
+
 test("compression: buildPlanMilestonePrompt minimal drops project/requirements/decisions files", () => {
   // The plan-milestone builder should gate root file inlining on inlineLevel
   assert.ok(