diff --git a/docs/agents.md b/docs/agents.md
index 687b78d3e0..0985a3e09e 100644
--- a/docs/agents.md
+++ b/docs/agents.md
@@ -479,7 +479,7 @@ The **Token Usage** panel in Agents view is derived from each agent's persisted
 
 Fusion exposes cache-hit metrics across logs, API, and CLI:
 
-- **Structured logs:** `token-cache-metrics` channel emits per-persist records with `taskId`, `agentId`, `role`, `inputTokens`, `cachedTokens`, `cacheWriteTokens`, and computed `hitRatio`.
+- **Structured logs:** `token-cache-metrics` channel emits per-persist records with `taskId`, `agentId`, `role`, `inputTokens`, `cachedTokens`, `cacheWriteTokens`, and computed `hitRatio`. Emission is `debug`-gated (`FUSION_DEBUG=token-cache-metrics` or `FUSION_DEBUG=1`); it is off in the default TUI log pane.
 - **Agent API:** `GET /api/agents/:id/token-usage` returns `last24h`, `last7d`, and `allTime` window summaries for permanent agents.
 - **CLI rollup:** run `pnpm fn:cache-stats` (or `pnpm fn:cache-stats --json`) for project-wide role totals plus per-permanent-agent cache-hit summaries.
 
diff --git a/docs/diagnostics.md b/docs/diagnostics.md
index 8b23b15fca..1a0601ba6f 100644
--- a/docs/diagnostics.md
+++ b/docs/diagnostics.md
@@ -21,7 +21,7 @@ FUSION_DEBUG=1                # everything (also: true, all, *)
 
 The variable is re-read per call, so it can be toggled on a long-lived process without recreating loggers. Debug lines emit under the `info` severity marker and render like any other info line.
 
-Currently debug-gated classes include local/default routing, capacity and re-entrancy skips, poll/sweep no-actions, per-step success/progress, optional integration probes, and successful verification bookkeeping. State-changing recovery and dispatch outcomes remain visible.
+Currently debug-gated classes include local/default routing, capacity and re-entrancy skips, poll/sweep no-actions, per-step success/progress, optional integration probes, successful verification bookkeeping, per-session agent setup (`agent-session` runtime/fallback resolution, planning mode, stuck-detector track bookkeeping), intentional skill-exclusion notices (`[skills] info: … disabled by project execution settings`), expected-missing PROMPT.md seed reads (ENOENT), token-cache metrics JSON, duplicate runtime `Specifying …` echoes, and zero-count recovery summaries. State-changing recovery and dispatch outcomes remain visible.
 
 Dashboard server code uses the core logger only: `import { createLogger } from "@fusion/core";`. Do not import an engine logger, use a relative cross-package logger path, or add a dashboard-local logger implementation.
 
diff --git a/packages/engine/src/__tests__/agent-skills-flow.test.ts b/packages/engine/src/__tests__/agent-skills-flow.test.ts
index 3c6b785c35..69b44baa4d 100644
--- a/packages/engine/src/__tests__/agent-skills-flow.test.ts
+++ b/packages/engine/src/__tests__/agent-skills-flow.test.ts
@@ -140,19 +140,19 @@ describe("agent skills flow - full integration", () => {
     expect(overrideResult.skills).toHaveLength(1);
     expect(overrideResult.skills[0].name).toBe("review");
 
-    // Step 9: Verify warning diagnostic for disabled lint skill
-    const disabledLintWarning = overrideResult.diagnostics.find(d =>
+    // Step 9: Intentional exclusion is an info diagnostic (debug-gated), not a warning
+    const disabledLintDiagnostic = overrideResult.diagnostics.find(d =>
       d.message.includes("disabled") && d.message.includes("lint")
     );
-    expect(disabledLintWarning).toBeDefined();
-    expect(disabledLintWarning?.type).toBe("warning");
+    expect(disabledLintDiagnostic).toBeDefined();
+    expect(disabledLintDiagnostic?.type).toBe("info");
 
-    // Step 10: Verify structured logger warning was called with disabled skill warning
-    const loggedMessages = mockPiLog.warn.mock.calls.map(c => c[0] as string);
-    const hasDisabledLintWarning = loggedMessages.some(m =>
+    // Step 10: Emission goes to piLog.debug, not warn
+    const loggedMessages = mockPiLog.debug.mock.calls.map(c => c[0] as string);
+    const hasDisabledLintNotice = loggedMessages.some(m =>
       m.includes("disabled") && m.includes("lint")
     );
-    expect(hasDisabledLintWarning).toBe(true);
+    expect(hasDisabledLintNotice).toBe(true);
   });
 
   it("flow with no exclusion pattern - both review and lint requested", async () => {
diff --git a/packages/engine/src/__tests__/log-severity-manifest.ts b/packages/engine/src/__tests__/log-severity-manifest.ts
index fb9d638e90..8422da0418 100644
--- a/packages/engine/src/__tests__/log-severity-manifest.ts
+++ b/packages/engine/src/__tests__/log-severity-manifest.ts
@@ -86,4 +86,15 @@ export const logSeverityManifest: SeverityManifestEntry[] = [
   { pkg: "dashboard", file: "terminal-service.ts", anchor: "Working directory does not exist: ${cwd}", priorSeverity: "warn", severity: "debug" },
   { pkg: "dashboard", file: "terminal-service.ts", anchor: "terminalLog.debug(`Session ${sessionId} not found`);", priorSeverity: "warn", severity: "debug" },
   { pkg: "dashboard", file: "terminal-service.ts", anchor: "Session ${sessionId} not found for resize", priorSeverity: "warn", severity: "debug" },
+  /*
+  FNXC:EngineDiagnostics 2026-08-01-18:11:
+  TUI flood demotions from operator log review. Anchors must share a source line with
+  `.debug(` (manifest is line-scoped). Multi-line sessionLog.debug setups, Tracking-task
+  triple sites, and zero-recovery gates are pinned in the spam-contract suite instead.
+  */
+  { pkg: "engine", file: "triage.ts", anchor: "planLog.debug(`${task.id}: planning in ${leanPlanning ? \"fast\" : \"standard\"} mode`)", priorSeverity: "log", severity: "debug" },
+  { pkg: "engine", file: "session-token-usage.ts", anchor: "cacheMetricsLog.debug(JSON.stringify({", priorSeverity: "log", severity: "debug" },
+  { pkg: "engine", file: "executor.ts", anchor: "tokenCacheMetricsLog.debug(JSON.stringify({", priorSeverity: "log", severity: "debug" },
+  { pkg: "engine", file: "runtimes/in-process-runtime.ts", anchor: "runtimeLog.debug(`Specifying ${t.id}...`)", priorSeverity: "log", severity: "debug" },
+  { pkg: "engine", file: "triage.ts", anchor: "planLog.debug(`${taskId}: failed to read PROMPT.md during ${context} (${promptPath}): ${msg}`)", priorSeverity: "warn", severity: "debug" },
 ];
diff --git a/packages/engine/src/__tests__/log-severity-spam-contract.test.ts b/packages/engine/src/__tests__/log-severity-spam-contract.test.ts
index 94663a1e84..ef22b6eadb 100644
--- a/packages/engine/src/__tests__/log-severity-spam-contract.test.ts
+++ b/packages/engine/src/__tests__/log-severity-spam-contract.test.ts
@@ -129,6 +129,53 @@ describe("log severity spam contract (source)", () => {
     expect(triage).not.toMatch(/planLog\.log\(`\$\{task\.id\}: using model \$\{modelDesc\}`\)/);
   });
 
+  /*
+  FNXC:EngineDiagnostics 2026-08-01-18:11:
+  Operator TUI review: replan-session setup chatter, track bookkeeping, intentional skill
+  exclusions, zero-recovery no-ops, and metrics JSON must stay off default info/warn.
+  */
+  it("session setup, track bookkeeping, skill exclusion, and zero-recovery stay debug-gated", () => {
+    const session = readSrc("agent-session-helpers.ts");
+    const stuck = readSrc("stuck-task-detector.ts");
+    const triage = readSrc("triage.ts");
+    const resolver = readSrc("skill-resolver.ts");
+    const selfHealing = readSrc("self-healing.ts");
+    const mission = readSrc("mission-execution-loop.ts");
+    const runtime = readSrc("runtimes/in-process-runtime.ts");
+    const tokenUsage = readSrc("session-token-usage.ts");
+    const executor = readSrc("executor.ts");
+
+    expect(session).toMatch(/sessionLog\.debug\(\s*`\[\$\{sessionPurpose\}\] grok-cli fallback/);
+    expect(session).toMatch(/sessionLog\.debug\(\s*`\[\$\{sessionPurpose\}\] Using runtime/);
+    expect(session).not.toMatch(/sessionLog\.log\(\s*`\[\$\{sessionPurpose\}\] grok-cli fallback/);
+    expect(session).not.toMatch(/sessionLog\.log\(\s*`\[\$\{sessionPurpose\}\] Using runtime/);
+
+    expect(stuck).toMatch(/stuckLog\.debug\(`Tracking task \$\{trackingKey\}/);
+    expect(stuck).not.toMatch(/stuckLog\.log\(`Tracking task \$\{trackingKey\}/);
+
+    expect(triage).toMatch(/planLog\.debug\(`\$\{task\.id\}: planning in \$\{leanPlanning/);
+    expect(triage).not.toMatch(/planLog\.log\(`\$\{task\.id\}: planning in \$\{leanPlanning/);
+    expect(triage).toMatch(/if \(code === "ENOENT"\) \{\s*planLog\.debug\(`\$\{taskId\}: failed to read PROMPT\.md/);
+    expect(triage).toMatch(/planLog\.warn\(`\$\{taskId\}: failed to read PROMPT\.md during \$\{context\}/);
+
+    expect(resolver).toMatch(/exists but is disabled by project execution settings/);
+    expect(resolver).toMatch(/type: "info" as ResourceDiagnostic\["type"\],\s*message: `Skill at '\$\{excludedPath\}' exists but is disabled/);
+
+    expect(selfHealing).toMatch(/if \(clearedAgentIds\.size > 0\) \{\s*log\.log\(`Recovered \$\{clearedAgentIds\.size\} drifted/);
+    expect(selfHealing).toMatch(/log\.debug\(`Recovered \$\{clearedAgentIds\.size\} drifted durable agent task link/);
+
+    expect(mission).toMatch(/if \(recoveredCount > 0\) \{\s*loopLog\.log\(`Active mission recovery complete/);
+    expect(mission).toMatch(/loopLog\.debug\(`Active mission recovery complete: recovered \$\{recoveredCount\} features`\)/);
+
+    expect(runtime).toMatch(/runtimeLog\.debug\(`Specifying \$\{t\.id\}\.\.\.`\)/);
+    expect(runtime).not.toMatch(/runtimeLog\.log\(`Specifying \$\{t\.id\}\.\.\.`\)/);
+
+    expect(tokenUsage).toMatch(/cacheMetricsLog\.debug\(JSON\.stringify\(/);
+    expect(tokenUsage).not.toMatch(/cacheMetricsLog\.log\(JSON\.stringify\(/);
+    expect(executor).toMatch(/tokenCacheMetricsLog\.debug\(JSON\.stringify\(/);
+    expect(executor).not.toMatch(/tokenCacheMetricsLog\.log\(JSON\.stringify\(/);
+  });
+
   it("self-healing no-action/skip, worktree-pool probes, and ntfy bookkeeping use debug", () => {
     const sh = readSrc("self-healing.ts");
     const wt = readSrc("worktree-pool.ts");
diff --git a/packages/engine/src/__tests__/session-token-usage.test.ts b/packages/engine/src/__tests__/session-token-usage.test.ts
index 4acc0c4e19..3c6bf075de 100644
--- a/packages/engine/src/__tests__/session-token-usage.test.ts
+++ b/packages/engine/src/__tests__/session-token-usage.test.ts
@@ -55,33 +55,40 @@ describe("accumulateSessionTokenUsage", () => {
   });
 
   it("writes initial token usage and emits cache metrics log", async () => {
+    const prevDebug = process.env.FUSION_DEBUG;
+    process.env.FUSION_DEBUG = "token-cache-metrics";
     const errorSpy = vi.spyOn(console, "error").mockImplementation(() => {});
-    const store = createStore(undefined);
-    const session = createSession({ tokens: { input: 100, output: 30, cacheRead: 5, cacheWrite: 2 } });
+    try {
+      const store = createStore(undefined);
+      const session = createSession({ tokens: { input: 100, output: 30, cacheRead: 5, cacheWrite: 2 } });
 
-    await accumulateSessionTokenUsage(store, "FN-1", session, { agentId: "agent-1", role: "reviewer" });
+      await accumulateSessionTokenUsage(store, "FN-1", session, { agentId: "agent-1", role: "reviewer" });
 
-    expect(store.updateTask).toHaveBeenCalledTimes(1);
-    const call = store.updateTask.mock.calls[0]![1] as { tokenUsage: Task["tokenUsage"] };
-    expect(call.tokenUsage).toMatchObject({
-      inputTokens: 100,
-      outputTokens: 30,
-      cachedTokens: 5,
-      cacheWriteTokens: 2,
-      totalTokens: 137,
-    });
-    const cacheLogCall = errorSpy.mock.calls.find((entry) => String(entry[0]).includes("[token-cache-metrics]"));
-    expect(cacheLogCall).toBeTruthy();
-    const payload = JSON.parse(String(cacheLogCall?.[0] ?? "").replace(/^.*\[token-cache-metrics\]\s*/, ""));
-    expect(payload).toMatchObject({
-      taskId: "FN-1",
-      agentId: "agent-1",
-      role: "reviewer",
-      inputTokens: 100,
-      cachedTokens: 5,
-      cacheWriteTokens: 2,
-      hitRatio: computeCacheHitRatio(100, 5),
-    });
+      expect(store.updateTask).toHaveBeenCalledTimes(1);
+      const call = store.updateTask.mock.calls[0]![1] as { tokenUsage: Task["tokenUsage"] };
+      expect(call.tokenUsage).toMatchObject({
+        inputTokens: 100,
+        outputTokens: 30,
+        cachedTokens: 5,
+        cacheWriteTokens: 2,
+        totalTokens: 137,
+      });
+      const cacheLogCall = errorSpy.mock.calls.find((entry) => String(entry[0]).includes("[token-cache-metrics]"));
+      expect(cacheLogCall).toBeTruthy();
+      const payload = JSON.parse(String(cacheLogCall?.[0] ?? "").replace(/^.*\[token-cache-metrics\]\s*/, ""));
+      expect(payload).toMatchObject({
+        taskId: "FN-1",
+        agentId: "agent-1",
+        role: "reviewer",
+        inputTokens: 100,
+        cachedTokens: 5,
+        cacheWriteTokens: 2,
+        hitRatio: computeCacheHitRatio(100, 5),
+      });
+    } finally {
+      if (prevDebug === undefined) delete process.env.FUSION_DEBUG;
+      else process.env.FUSION_DEBUG = prevDebug;
+    }
   });
 
   it("uses an explicit task-start baseline to exclude resumed-session lifetime tokens", async () => {
@@ -220,23 +227,30 @@ describe("accumulateSessionTokenUsage", () => {
   });
 
   it("emits token-cache-metrics log when executor persists non-zero delta", async () => {
+    const prevDebug = process.env.FUSION_DEBUG;
+    process.env.FUSION_DEBUG = "token-cache-metrics";
     const errorSpy = vi.spyOn(console, "error").mockImplementation(() => {});
-    const store = createStore(undefined);
-    const executor = Object.create(TaskExecutor.prototype) as any;
-    executor.store = store;
-    executor.tokenUsageBaselines = new Map();
-    executor.activeSessions = new Map();
-    executor.currentRunContexts = new Map();
+    try {
+      const store = createStore(undefined);
+      const executor = Object.create(TaskExecutor.prototype) as any;
+      executor.store = store;
+      executor.tokenUsageBaselines = new Map();
+      executor.activeSessions = new Map();
+      executor.currentRunContexts = new Map();
 
-    await executor.persistTokenUsage("FN-1", {
-      getSessionStats: () => ({ tokens: { input: 3, output: 2, cacheRead: 1, cacheWrite: 0, total: 6 } }),
-      model: { provider: "mock", id: "scripted" },
-    });
+      await executor.persistTokenUsage("FN-1", {
+        getSessionStats: () => ({ tokens: { input: 3, output: 2, cacheRead: 1, cacheWrite: 0, total: 6 } }),
+        model: { provider: "mock", id: "scripted" },
+      });
 
-    const cacheLogCall = errorSpy.mock.calls.find((entry) => String(entry[0]).includes("[token-cache-metrics]"));
-    expect(cacheLogCall).toBeTruthy();
-    const call = store.updateTask.mock.calls[0]![1] as { tokenUsage: Task["tokenUsage"] };
-    expect(call.tokenUsage).toMatchObject({ modelProvider: "mock", modelId: "scripted" });
+      const cacheLogCall = errorSpy.mock.calls.find((entry) => String(entry[0]).includes("[token-cache-metrics]"));
+      expect(cacheLogCall).toBeTruthy();
+      const call = store.updateTask.mock.calls[0]![1] as { tokenUsage: Task["tokenUsage"] };
+      expect(call.tokenUsage).toMatchObject({ modelProvider: "mock", modelId: "scripted" });
+    } finally {
+      if (prevDebug === undefined) delete process.env.FUSION_DEBUG;
+      else process.env.FUSION_DEBUG = prevDebug;
+    }
   });
 
   it("enforces soft and hard budgets through the real persist helper exactly once", async () => {
diff --git a/packages/engine/src/__tests__/skill-resolver.test.ts b/packages/engine/src/__tests__/skill-resolver.test.ts
index a511b775f3..f1d7bc736f 100644
--- a/packages/engine/src/__tests__/skill-resolver.test.ts
+++ b/packages/engine/src/__tests__/skill-resolver.test.ts
@@ -689,7 +689,8 @@ describe("createSkillsOverrideFromSelection", () => {
 
       expect(result.skills).toHaveLength(0);
       expect(result.diagnostics).toHaveLength(1);
-      expect(result.diagnostics[0].type).toBe("warning");
+      // Intentional exclusions are info diagnostics (debug-gated emission), not warn.
+      expect(result.diagnostics[0].type).toBe("info");
       expect(result.diagnostics[0].message).toContain("disabled by project execution settings");
       expect(result.diagnostics.some((diagnostic) => diagnostic.message.includes("not found"))).toBe(false);
     });
@@ -791,7 +792,7 @@ describe("createSkillsOverrideFromSelection", () => {
       expect(lastCall).toContain("missing-skill");
     });
 
-    it("produces warning diagnostic for disabled skills (exists but excluded by patterns)", () => {
+    it("produces info diagnostic for disabled skills (exists but excluded by patterns)", () => {
       // Simulate a skill that exists but was disabled by project exclusion pattern
       const selection: SkillSelectionResult = {
         allowedSkillPaths: new Set<string>(),
@@ -817,15 +818,16 @@ describe("createSkillsOverrideFromSelection", () => {
       // Skill should be filtered out (excluded)
       expect(result.skills).toHaveLength(0);
 
-      // Should produce warning diagnostic for disabled skill (ResourceDiagnostic only supports warning|error|collision)
+      // Intentional exclusions are info (debug-gated emission), not operator warnings
       expect(result.diagnostics).toHaveLength(1);
-      expect(result.diagnostics[0].type).toBe("warning");
+      expect(result.diagnostics[0].type).toBe("info");
       expect(result.diagnostics[0].message).toContain("disabled");
       expect(result.diagnostics[0].message).toContain("disabled-skill");
 
-      // Verify logging
-      expect(mockPiLog.warn).toHaveBeenCalled();
-      const lastCall = mockPiLog.warn.mock.calls[mockPiLog.warn.mock.calls.length - 1][0] as string;
+      // Verify logging routes to debug, not warn
+      expect(mockPiLog.warn).not.toHaveBeenCalled();
+      expect(mockPiLog.debug).toHaveBeenCalled();
+      const lastCall = mockPiLog.debug.mock.calls[mockPiLog.debug.mock.calls.length - 1][0] as string;
       expect(lastCall).toContain("disabled");
     });
 
@@ -1224,7 +1226,7 @@ describe("createSkillsOverrideFromSelection", () => {
 
       expect(result.skills).toEqual([]);
       expect(result.diagnostics).toContainEqual(expect.objectContaining({
-        type: "warning",
+        type: "info",
         message: expect.stringContaining("disabled by project execution settings"),
       }));
     });
diff --git a/packages/engine/src/agent-session-helpers.ts b/packages/engine/src/agent-session-helpers.ts
index 5e0fda0ce8..94531a9b54 100644
--- a/packages/engine/src/agent-session-helpers.ts
+++ b/packages/engine/src/agent-session-helpers.ts
@@ -984,7 +984,13 @@ export async function createResolvedAgentSession(
       `[${sessionPurpose}] configured grok-cli fallback "${runtimeOptions.fallbackModelId ?? "unknown"}" dropped: no Fusion-visible GROK_API_KEY and the Grok CLI runtime plugin is unavailable; primary "${runtimeOptions.defaultProvider}/${runtimeOptions.defaultModelId}" is unchanged. Install/enable the Grok CLI runtime plugin or set GROK_API_KEY.`,
     );
   } else if (deferredGrokFallback) {
-    sessionLog.log(
+    /*
+    FNXC:EngineDiagnostics 2026-08-01-18:11:
+    Deferred grok-cli fallback is the expected no-visible-key config path and fires on every
+    session create. Real engagement already warns + audits `session:grok-cli-fallback-engaged`;
+    keep the deferral notice on debug (FUSION_DEBUG=agent-session) so the TUI is not flooded.
+    */
+    sessionLog.debug(
       `[${sessionPurpose}] grok-cli fallback "${deferredGrokFallback.modelId ?? "unknown"}" deferred to the Grok CLI runtime: it engages only if primary "${runtimeOptions.defaultProvider}/${runtimeOptions.defaultModelId}" fails with a retryable model error.`,
     );
   }
@@ -997,7 +1003,12 @@ export async function createResolvedAgentSession(
     }
     : await resolveRuntime(buildRuntimeResolutionContext(sessionPurpose, pluginRunner, effectiveRuntimeHint));
 
-  sessionLog.log(
+  /*
+  FNXC:EngineDiagnostics 2026-08-01-18:11:
+  Runtime resolution is per-session setup chatter (same class as demoted planning `using model`).
+  Audit already records `session:runtime-resolved`; keep the TUI line on debug (FUSION_DEBUG=agent-session).
+  */
+  sessionLog.debug(
     `[${sessionPurpose}] Using runtime "${resolved.runtimeId}" (configured=${resolved.wasConfigured})`,
   );
 
diff --git a/packages/engine/src/executor.ts b/packages/engine/src/executor.ts
index 17d9c41cf5..ccbec31cdd 100644
--- a/packages/engine/src/executor.ts
+++ b/packages/engine/src/executor.ts
@@ -5145,7 +5145,12 @@ export class TaskExecutor {
     if (!merged) return;
     const tokenUsage = this.tokenUsageWithModelSnapshot(merged, activeSession, task.tokenUsage, delta);
 
-    tokenCacheMetricsLog.log(JSON.stringify({
+    /*
+    FNXC:EngineDiagnostics 2026-08-01-18:11:
+    Executor token-cache metrics mirror session-token-usage: debug-only telemetry
+    (FUSION_DEBUG=token-cache-metrics), not default TUI noise.
+    */
+    tokenCacheMetricsLog.debug(JSON.stringify({
       taskId,
       agentId: task.assignedAgentId ?? undefined,
       role: "executor",
diff --git a/packages/engine/src/mission-execution-loop.ts b/packages/engine/src/mission-execution-loop.ts
index 4e2e5263fb..77cee275ee 100644
--- a/packages/engine/src/mission-execution-loop.ts
+++ b/packages/engine/src/mission-execution-loop.ts
@@ -477,7 +477,16 @@ export class MissionExecutionLoop extends EventEmitter {
         }
       }
 
-      loopLog.log(`Active mission recovery complete: recovered ${recoveredCount} features`);
+      /*
+      FNXC:EngineDiagnostics 2026-08-01-18:11:
+      Zero-feature recovery complete is a startup no-op — debug only (FUSION_DEBUG=mission-loop).
+      Non-zero recoveries stay on log as operator-visible state repairs.
+      */
+      if (recoveredCount > 0) {
+        loopLog.log(`Active mission recovery complete: recovered ${recoveredCount} features`);
+      } else {
+        loopLog.debug(`Active mission recovery complete: recovered ${recoveredCount} features`);
+      }
       return { recoveredCount };
     } catch (err) {
       loopLog.error("Error during active mission recovery:", err);
diff --git a/packages/engine/src/runtimes/in-process-runtime.ts b/packages/engine/src/runtimes/in-process-runtime.ts
index fbe9621341..1215ef8f50 100644
--- a/packages/engine/src/runtimes/in-process-runtime.ts
+++ b/packages/engine/src/runtimes/in-process-runtime.ts
@@ -1559,7 +1559,12 @@ export class InProcessRuntime
           acquirePlanningWorktree: (taskId) => this.executor.ensureTaskWorktreeForPlanning(taskId),
           onSpecifyStart: (t) => {
             this.recordActivity();
-            runtimeLog.log(`Specifying ${t.id}...`);
+            /*
+            FNXC:EngineDiagnostics 2026-08-01-18:11:
+            Duplicate of triage's richer `Specifying ${id}: ${title}` planLog line. Keep this
+            short runtime echo on debug (FUSION_DEBUG=runtime) so planning start is not double-logged.
+            */
+            runtimeLog.debug(`Specifying ${t.id}...`);
           },
           onSpecifyComplete: (t, report) => {
             // Activity is recorded for EVERY outcome: a planning session ran either
diff --git a/packages/engine/src/self-healing.ts b/packages/engine/src/self-healing.ts
index b263860256..e97c38f70b 100644
--- a/packages/engine/src/self-healing.ts
+++ b/packages/engine/src/self-healing.ts
@@ -13355,7 +13355,16 @@ const movedTask = await this.store.moveTask(task.id, completeLane);
       log.log(`Cleared drifted durable agent task link for ${agent.id} (${linkedTaskId}): ${reason}; file-scope lease preserved when present`);
     }
 
-    log.log(`Recovered ${clearedAgentIds.size} drifted durable agent task link(s)`);
+    /*
+    FNXC:EngineDiagnostics 2026-08-01-18:11:
+    Zero-recovery summary is a no-op sweep result — debug only (FUSION_DEBUG=self-healing).
+    Non-zero recoveries stay on log so operators still see real link repairs.
+    */
+    if (clearedAgentIds.size > 0) {
+      log.log(`Recovered ${clearedAgentIds.size} drifted durable agent task link(s)`);
+    } else {
+      log.debug(`Recovered ${clearedAgentIds.size} drifted durable agent task link(s)`);
+    }
     return clearedAgentIds.size;
   }
 
diff --git a/packages/engine/src/session-token-usage.ts b/packages/engine/src/session-token-usage.ts
index dbbec5684c..b75fa3f5dc 100644
--- a/packages/engine/src/session-token-usage.ts
+++ b/packages/engine/src/session-token-usage.ts
@@ -167,7 +167,12 @@ export async function accumulateSessionTokenUsage(
       }, model, now),
     };
 
-    cacheMetricsLog.log(JSON.stringify({
+    /*
+    FNXC:EngineDiagnostics 2026-08-01-18:11:
+    Per-persist token cache metrics are structured telemetry, not operator state changes.
+    Gate on FUSION_DEBUG=token-cache-metrics so the TUI is not filled with JSON every session end.
+    */
+    cacheMetricsLog.debug(JSON.stringify({
       taskId,
       agentId: options?.agentId,
       role,
diff --git a/packages/engine/src/skill-resolver.ts b/packages/engine/src/skill-resolver.ts
index 3133fae2b6..e1222b8fed 100644
--- a/packages/engine/src/skill-resolver.ts
+++ b/packages/engine/src/skill-resolver.ts
@@ -519,8 +519,14 @@ export function createSkillsOverrideFromSelection(
 
     for (const excludedPath of excludedSkillPaths) {
       if (hasDiscoveredMatch(excludedPath)) {
+        /*
+        FNXC:EngineDiagnostics 2026-08-01-18:11:
+        Intentional project skill exclusions are expected config, not operator degradation.
+        Use type=info so emission paths route to piLog.debug (FUSION_DEBUG=pi) instead of
+        warn-flooding the TUI on every session that rediscovers the same disabled skill.
+        */
         newDiagnostics.push({
-          type: "warning",
+          type: "info" as ResourceDiagnostic["type"],
           message: `Skill at '${excludedPath}' exists but is disabled by project execution settings${purpose}`,
           path: excludedPath,
         });
diff --git a/packages/engine/src/stuck-task-detector.ts b/packages/engine/src/stuck-task-detector.ts
index 72029d86e6..4602e26dad 100644
--- a/packages/engine/src/stuck-task-detector.ts
+++ b/packages/engine/src/stuck-task-detector.ts
@@ -338,19 +338,30 @@ export class StuckTaskDetector {
           }
           this.exhaustedTasks.delete(canonicalId);
           this.tracked.set(trackingKey, emptyTrackedTask(session, Date.now(), canonicalId));
-          stuckLog.log(`Tracking task ${trackingKey} (canonical=${canonicalId}, total tracked: ${this.tracked.size})`);
+          /*
+          FNXC:EngineDiagnostics 2026-08-01-18:11:
+          Track/untrack bookkeeping fires on every session start and flooded the TUI during
+          replan storms. Keep on debug (FUSION_DEBUG=stuck-detector); real stuck detections
+          and terminal-skip/error paths stay on log/warn/error.
+          */
+          stuckLog.debug(`Tracking task ${trackingKey} (canonical=${canonicalId}, total tracked: ${this.tracked.size})`);
         })
         .catch((err) => {
           stuckLog.error(`Failed to validate exhausted status for ${canonicalId}; proceeding to track:`, err);
           this.exhaustedTasks.delete(canonicalId);
           this.tracked.set(trackingKey, emptyTrackedTask(session, Date.now(), canonicalId));
-          stuckLog.log(`Tracking task ${trackingKey} (canonical=${canonicalId}, total tracked: ${this.tracked.size})`);
+          stuckLog.debug(`Tracking task ${trackingKey} (canonical=${canonicalId}, total tracked: ${this.tracked.size})`);
         });
       return;
     }
 
     this.tracked.set(trackingKey, emptyTrackedTask(session, Date.now(), canonicalId));
-    stuckLog.log(`Tracking task ${trackingKey} (canonical=${canonicalId}, total tracked: ${this.tracked.size})`);
+    /*
+    FNXC:EngineDiagnostics 2026-08-01-18:11:
+    Track bookkeeping is steady-state session lifecycle chatter — debug only
+    (FUSION_DEBUG=stuck-detector). Stuck detections remain log/warn/error.
+    */
+    stuckLog.debug(`Tracking task ${trackingKey} (canonical=${canonicalId}, total tracked: ${this.tracked.size})`);
   }
 
   /**
diff --git a/packages/engine/src/triage.ts b/packages/engine/src/triage.ts
index 2595dffa23..fbbd54f349 100644
--- a/packages/engine/src/triage.ts
+++ b/packages/engine/src/triage.ts
@@ -1449,7 +1449,18 @@ export class TriageProcessor {
     const promptPath = join(this.rootDir, ".fusion", "tasks", taskId, "PROMPT.md");
     const written = await readFile(promptPath, "utf-8").catch((err: unknown) => {
       const msg = err instanceof Error ? err.message : String(err);
-      planLog.warn(`${taskId}: failed to read PROMPT.md during ${context} (${promptPath}): ${msg}`);
+      const code = err && typeof err === "object" && "code" in err ? String((err as { code?: unknown }).code) : undefined;
+      /*
+      FNXC:EngineDiagnostics 2026-08-01-18:11:
+      needs-replan revision seed commonly has no PROMPT.md yet (ENOENT) — that is an expected
+      cold/fresh respec path, not operator degradation. Demote missing-file to debug
+      (FUSION_DEBUG=plan); keep warn for unexpected I/O so real disk failures stay visible.
+      */
+      if (code === "ENOENT") {
+        planLog.debug(`${taskId}: failed to read PROMPT.md during ${context} (${promptPath}): ${msg}`);
+      } else {
+        planLog.warn(`${taskId}: failed to read PROMPT.md during ${context} (${promptPath}): ${msg}`);
+      }
       return "";
     });
     return written.trim().length > 0 ? written : undefined;
@@ -2589,7 +2600,12 @@ export class TriageProcessor {
             planLog.warn(`${task.id}: failed to resolve triage agent instructions, continuing with defaults: ${msg}`);
           }
         }
-        planLog.log(`${task.id}: planning in ${leanPlanning ? "fast" : "standard"} mode`);
+        /*
+        FNXC:EngineDiagnostics 2026-08-01-18:11:
+        Lean vs standard planning mode is config-derived setup and fires every planning attempt.
+        Same flood class as demoted `using model` — keep on debug (FUSION_DEBUG=plan).
+        */
+        planLog.debug(`${task.id}: planning in ${leanPlanning ? "fast" : "standard"} mode`);
         const triageIdentitySection = assignedAgent
           ? `## Identity\n\nYou are ${assignedAgent.name}${assignedAgent.title?.trim() ? `, ${assignedAgent.title.trim()}` : ""} (agent ID: ${assignedAgent.id}, role: ${assignedAgent.role}).`
           : "";