diff --git a/packages/loopover-miner/lib/idea-feasibility-cli.js b/packages/loopover-miner/lib/idea-feasibility-cli.js
index 8350656830..c93896d733 100644
--- a/packages/loopover-miner/lib/idea-feasibility-cli.js
+++ b/packages/loopover-miner/lib/idea-feasibility-cli.js
@@ -33,7 +33,9 @@ export function parseIdeaFeasibilityArgs(args) {
     }
     if (token === "--hint") {
       const value = args[i + 1];
-      if (value === undefined || value.startsWith("-")) {
+      // A whitespace-only hint is as empty as a missing one (#6766): it declares no testable success signal, so
+      // it gets the same rejection rather than sailing through as a real objective signal.
+      if (value === undefined || value.startsWith("-") || value.trim() === "") {
         return { error: "--hint requires a value." };
       }
       options.acceptanceHints.push(value);
diff --git a/packages/loopover-miner/lib/idea-feasibility.js b/packages/loopover-miner/lib/idea-feasibility.js
index 0c6d24263f..0fed105d9c 100644
--- a/packages/loopover-miner/lib/idea-feasibility.js
+++ b/packages/loopover-miner/lib/idea-feasibility.js
@@ -36,7 +36,11 @@ export function deriveIdeaIssueStatus(idea, resolved) {
   // Out of the loop's scope: the idea does not resolve to a repo the loop can act on.
   if (!resolved.targetResolvable) return "missing";
   // Impossible to evaluate objectively: no declared success signal, so the loop could never test its own output.
-  const objectiveSignals = idea.acceptanceHints?.length ?? 0;
+  // Count CONTENT, not array length (#6766): a blank/whitespace-only hint declares nothing testable, so it must
+  // not pass as an objective signal just by occupying a slot.
+  const objectiveSignals = (idea.acceptanceHints ?? []).filter(
+    (hint) => typeof hint === "string" && hint.trim() !== "",
+  ).length;
   if (objectiveSignals === 0) return "invalid";
   return "ready";
 }
diff --git a/test/unit/miner-idea-feasibility-cli.test.ts b/test/unit/miner-idea-feasibility-cli.test.ts
index 6ff0f96aa7..99ff4e7278 100644
--- a/test/unit/miner-idea-feasibility-cli.test.ts
+++ b/test/unit/miner-idea-feasibility-cli.test.ts
@@ -71,6 +71,15 @@ describe("parseIdeaFeasibilityArgs (#5671)", () => {
     });
   });
 
+  it("REGRESSION (#6766): rejects a whitespace-only --hint the same way as a missing one", () => {
+    // A blank hint declares no testable success signal, so it must not sail through as a real one.
+    for (const blank of ["   ", "\t", " \n "]) {
+      expect(parseIdeaFeasibilityArgs(["unclaimed", "none", "--hint", blank])).toEqual({
+        error: "--hint requires a value.",
+      });
+    }
+  });
+
   it("rejects --hint whose value looks like another flag", () => {
     expect(parseIdeaFeasibilityArgs(["unclaimed", "none", "--hint", "--json"])).toEqual({
       error: "--hint requires a value.",
diff --git a/test/unit/miner-idea-feasibility.test.ts b/test/unit/miner-idea-feasibility.test.ts
index 3eaaa352ea..61f194d541 100644
--- a/test/unit/miner-idea-feasibility.test.ts
+++ b/test/unit/miner-idea-feasibility.test.ts
@@ -28,6 +28,17 @@ describe("deriveIdeaIssueStatus (#5671)", () => {
     expect(deriveIdeaIssueStatus({ acceptanceHints: [] }, { targetResolvable: true })).toBe("invalid");
   });
 
+  it("REGRESSION (#6766): returns 'invalid' for blank/whitespace-only hints — a slot is not a signal", () => {
+    // The count used to be array LENGTH, so a whitespace-only hint declared nothing testable yet passed as
+    // "ready", contradicting the module's own "no objective success signal is invalid" contract.
+    expect(deriveIdeaIssueStatus({ acceptanceHints: ["   "] }, { targetResolvable: true })).toBe("invalid");
+    expect(deriveIdeaIssueStatus({ acceptanceHints: ["", "\t", "\n  "] }, { targetResolvable: true })).toBe("invalid");
+  });
+
+  it("REGRESSION (#6766): a real hint alongside blank ones still counts as an objective signal", () => {
+    expect(deriveIdeaIssueStatus({ acceptanceHints: ["  ", "retries on 5xx"] }, { targetResolvable: true })).toBe("ready");
+  });
+
   it("returns 'ready' when the idea resolves and carries at least one objective success signal", () => {
     expect(deriveIdeaIssueStatus({ acceptanceHints: ["uploads retry on 5xx"] }, { targetResolvable: true })).toBe("ready");
   });