diff --git a/agents/opencode.ts b/agents/opencode.ts
index e0da910..7aefcc4 100644
--- a/agents/opencode.ts
+++ b/agents/opencode.ts
@@ -80,6 +80,26 @@ type OpenCodeConfig = {
  */
 const PULLFROG_OPENCODE_OUTPUT_LIMIT = 5000;
 
+/**
+ * upstream opencode hardcodes `thinkingLevel: "high"` as the default for every
+ * gemini-3 model on the direct google SDK (`provider/transform.ts` `options()`).
+ * that adds 30-60s of pre-tool-call TTFT and 5-46s of post-tool jabber per turn,
+ * which is overkill for agentic loops where most steps are tool-routing
+ * decisions. we override to "medium" for the curated slugs we ship in
+ * `action/models.ts`; users who want max quality can still pick the `-high`
+ * variant explicitly. flash stays at "medium" too — low-effort flash is
+ * visibly worse on harder tasks and the latency savings aren't meaningful
+ * (flash is already fast). other gemini-3 ids that exist in models.dev but
+ * aren't in our curated alias map keep the upstream `"high"` default.
+ *
+ * keyed by upstream api id (matches the slugs in `action/models.ts`). the
+ * merge order in opencode `session/llm.ts` is `base ← model.options ← agent.options ← variant`,
+ * deep-merged — so an explicit `--variant high` still wins, and explicit
+ * model.options in a user-provided opencode config would also win.
+ */
+const GEMINI_3_DIRECT_THINKING_LEVEL = "medium";
+const GEMINI_3_DIRECT_API_IDS = ["gemini-3.1-pro-preview", "gemini-3-flash-preview"];
+
 function buildSecurityConfig(ctx: AgentRunContext, model: string | undefined): string {
   const config: OpenCodeConfig = {
     permission: {
@@ -94,6 +114,20 @@ function buildSecurityConfig(ctx: AgentRunContext, model: string | undefined): s
       [pullfrogMcpName]: { type: "remote", url: ctx.mcpServerUrl },
     },
     agent: buildReviewerAgentConfig(),
+    provider: {
+      google: {
+        models: Object.fromEntries(
+          GEMINI_3_DIRECT_API_IDS.map((id) => [
+            id,
+            {
+              options: {
+                thinkingConfig: { thinkingLevel: GEMINI_3_DIRECT_THINKING_LEVEL },
+              },
+            },
+          ])
+        ),
+      },
+    },
   };
 
   if (model) {
diff --git a/agents/postRun.ts b/agents/postRun.ts
index 58d5d3e..35c64ea 100644
--- a/agents/postRun.ts
+++ b/agents/postRun.ts
@@ -1,5 +1,6 @@
 import { readFile } from "node:fs/promises";
 import { LIFECYCLE_HOOK_TIMEOUT_MS } from "../lifecycle.ts";
+import { NON_COMMITTING_MODES } from "../modes.ts";
 import type { ToolState } from "../toolState.ts";
 import { log } from "../utils/cli.ts";
 import {
@@ -181,8 +182,21 @@ export async function collectPostRunIssues(
     const failure = await executeStopHook(ctx.stopScript);
     if (failure) issues.stopHook = failure;
   }
+  // dirty-tree gate fires only in modes that legitimately commit. Review /
+  // IncrementalReview / Plan complete via review submission or a Plan
+  // comment, not by touching files — any tree dirt is incidental (e.g. a
+  // tool-installed `node_modules/`) and the worktree is ephemeral, so
+  // nudging the agent to commit it would produce a spurious PR. see
+  // `NON_COMMITTING_MODES` in `action/modes.ts`.
   const status = getGitStatus();
-  if (status) issues.dirtyTree = status;
+  const mode = ctx.toolState.selectedMode;
+  if (status) {
+    if (mode && NON_COMMITTING_MODES.has(mode)) {
+      log.info(`» dirty-tree gate suppressed: mode \`${mode}\` does not commit`);
+    } else {
+      issues.dirtyTree = status;
+    }
+  }
   const summaryFilePath = ctx.toolState.summaryFilePath;
   const summarySeed = ctx.toolState.summarySeed;
   if (!options.skipSummaryStale && summaryFilePath && summarySeed !== undefined) {
diff --git a/modes.ts b/modes.ts
index 9bde11a..d713824 100644
--- a/modes.ts
+++ b/modes.ts
@@ -433,3 +433,18 @@ ${PR_SUMMARY_FORMAT}`,
 
 // static export for UI display — uses opencode format as the readable default
 export const modes: Mode[] = computeModes("opencode");
+
+/**
+ * modes that legitimately never modify the working tree. used by the post-run
+ * dirty-tree gate to suppress the "commit and push" nudge — those modes
+ * complete by submitting a review (`Review` / `IncrementalReview`) or by
+ * posting a Plan comment (`Plan`), not by touching files. any leftover in the
+ * tree at end-of-run is incidental tool noise (e.g. a `node_modules/` from a
+ * stray install attempt) on an ephemeral worktree; nudging the agent to
+ * commit it would produce a spurious PR.
+ */
+export const NON_COMMITTING_MODES: ReadonlySet<string> = new Set([
+  "Review",
+  "IncrementalReview",
+  "Plan",
+]);
diff --git a/prep/installNodeDependencies.ts b/prep/installNodeDependencies.ts
index d315217..034bb48 100644
--- a/prep/installNodeDependencies.ts
+++ b/prep/installNodeDependencies.ts
@@ -135,14 +135,21 @@ export const installNodeDependencies: PrepDefinition = {
       }
     }
 
-    // get the frozen install command (or fallback to regular install)
-    const resolved = resolveCommand(agent, "frozen", []) || resolveCommand(agent, "install", []);
+    // frozen-lockfile install only. eager prep is non-mutating by contract:
+    // we run it before the agent starts and any artifact it leaves in the
+    // tree (e.g. a generated `package-lock.json`) trips the dirty-tree
+    // post-run gate and produces a spurious PR. `frozen` commands
+    // (`npm ci`, `pnpm install --frozen-lockfile`, etc.) fail cleanly
+    // without modifying state when there's no lockfile, which is exactly
+    // what we want — repos that need a non-frozen install must opt in via
+    // a `setup` lifecycle hook (`action/utils/lifecycle.ts`).
+    const resolved = resolveCommand(agent, "frozen", []);
     if (!resolved) {
       return {
         language: "node",
         packageManager,
         dependenciesInstalled: false,
-        issues: [`no install command found for ${agent}`],
+        issues: [`no frozen-install command available for ${agent}`],
       };
     }