Delete unreachable thrash salvage matcher, hint, and class

CL-6936/PR #558 removed the re-read thrash stop, so no report can ever
carry a 'progressive thrash' Summary. Remove the now-dead
isThrashSubAgentReport/appendThrashParentHint/THRASH_PARENT_HINT in
stop-policy.ts, the classifyBriefSalvage thrash branch in
brief-dispatch.ts, and the 'thrash' entries in HARD_BLOCK_SALVAGES and
BriefSalvageKind. Other salvage kinds are untouched.

Author: TheGreatAxios

src/subagent/brief-dispatch.ts

@@ -20,13 +20,12 @@ import {
   isNoProgressSubAgentReport,
   isNoShipSubAgentReport,
   isRepetitionSubAgentReport,
-  isThrashSubAgentReport,
   isTurnBudgetSubAgentReport,
 } from "./stop-policy.js";
 
 /** Salvage classes that must not be re-dispatched with an identical brief. */
 export type HardBlockSalvage =
-  "thrash" | "no-ship" | "no-progress" | "repetition" | "never-acted" | "never-edited";
+  "no-ship" | "no-progress" | "repetition" | "never-acted" | "never-edited";
 
 export type BriefSalvageKind =
   HardBlockSalvage | "turn-budget" | "deadline" | "stalled" | "cancelled" | "incomplete-report";
@@ -54,7 +53,6 @@ export interface BriefDispatchRecord {
 export const TURN_BUDGET_STOP_AFTER_DISPATCHES = 3;
 
 const HARD_BLOCK_SALVAGES = new Set<BriefSalvageKind>([
-  "thrash",
   "no-ship",
   "no-progress",
   "repetition",
@@ -90,7 +88,6 @@ export function isIncompleteReportSubAgentReport(report: string): boolean {
  */
 export function classifyBriefSalvage(report: string): BriefSalvageKind | null {
   // Order: more specific salvage phrases first.
-  if (isThrashSubAgentReport(report)) return "thrash";
   if (isNoShipSubAgentReport(report)) return "no-ship";
   if (isRepetitionSubAgentReport(report)) return "repetition";
   if (isNeverEditedSubAgentReport(report)) return "never-edited";

src/subagent/index.test.ts

@@ -2146,19 +2146,19 @@ describe("brief re-dispatch ledger (CL-4343 / CL-5203)", () => {
     expect(changed).not.toBe(a);
   });
 
-  test("hard-blocks identical brief after thrash salvage; allows changed brief", () => {
+  test("hard-blocks identical brief after no-progress salvage; allows changed brief", () => {
     const ledger = createBriefDispatchLedger();
-    const fp = fingerprintTaskBrief({ prompt: "fix thrash", intent: "implement" });
+    const fp = fingerprintTaskBrief({ prompt: "fix no-progress job", intent: "implement" });
     expect(ledger.admit(fp).ok).toBe(true);
-    ledger.recordOutcome(fp, "thrash");
+    ledger.recordOutcome(fp, "no-progress");
     const blocked = ledger.admit(fp);
     expect(blocked.ok).toBe(false);
     if (blocked.ok) throw new Error("expected block");
     expect(blocked.message).toContain("refused re-dispatch");
-    expect(blocked.message).toContain("thrash");
+    expect(blocked.message).toContain("no-progress");
 
     const other = fingerprintTaskBrief({
-      prompt: "fix thrash with narrower scope",
+      prompt: "fix no-progress job with narrower scope",
       intent: "implement",
       successCriteria: ["one file only"],
     });
@@ -2183,7 +2183,7 @@ describe("brief re-dispatch ledger (CL-4343 / CL-5203)", () => {
     expect(second.dispatchCount).toBe(2);
   });
 
-  test("successful complete resets retry budget; thrash hard-block is sticky", () => {
+  test("successful complete resets retry budget; hard-block is sticky", () => {
     const ledger = createBriefDispatchLedger();
     const fp = fingerprintTaskBrief({ prompt: "ok job" });
     expect(ledger.admit(fp).ok).toBe(true);
@@ -2196,12 +2196,12 @@ describe("brief re-dispatch ledger (CL-4343 / CL-5203)", () => {
     if (!afterSuccess.ok) throw new Error("expected admit");
     expect(afterSuccess.dispatchCount).toBe(1);
 
-    // Thrash is sticky for the session — success on a concurrent twin must not clear it.
-    const thrashFp = fingerprintTaskBrief({ prompt: "thrash sticky" });
-    ledger.admit(thrashFp);
-    ledger.recordOutcome(thrashFp, "thrash");
-    ledger.recordOutcome(thrashFp, null);
-    expect(ledger.admit(thrashFp).ok).toBe(false);
+    // Hard-block salvage is sticky for the session — success on a concurrent twin must not clear it.
+    const stickyFp = fingerprintTaskBrief({ prompt: "no-progress sticky" });
+    ledger.admit(stickyFp);
+    ledger.recordOutcome(stickyFp, "no-progress");
+    ledger.recordOutcome(stickyFp, null);
+    expect(ledger.admit(stickyFp).ok).toBe(false);
   });
 
   test("release undoes admit when run never produces a body", () => {

src/subagent/index.ts

@@ -52,7 +52,6 @@ export {
   appendNoProgressParentHint,
   appendRepetitionParentHint,
   appendSubAgentParentHints,
-  appendThrashParentHint,
   appendTurnBudgetParentHint,
   evaluateSubAgentStop,
   fingerprintToolCalls,
@@ -62,7 +61,6 @@ export {
   isNeverEditedSubAgentReport,
   isNoProgressSubAgentReport,
   isRepetitionSubAgentReport,
-  isThrashSubAgentReport,
   isTurnBudgetSubAgentReport,
   nextToolCallStreak,
   partialTextFromEvent,

src/subagent/stop-policy.ts

@@ -530,12 +530,6 @@ export function isDeadlineSubAgentReport(report: string): boolean {
   return parsed.summary.includes("deadline reached");
 }
 
-/** True when the worker returned a progressive-thrash salvage report. */
-export function isThrashSubAgentReport(report: string): boolean {
-  const parsed = parseSubAgentReport(report);
-  return parsed.summary.includes("progressive thrash");
-}
-
 /** True when the worker returned a streamed-repetition salvage report. */
 export function isRepetitionSubAgentReport(report: string): boolean {
   const parsed = parseSubAgentReport(report);
@@ -558,9 +552,6 @@ const NEVER_EDITED_PARENT_HINT =
 const DEADLINE_PARENT_HINT =
   "[Sub-agent hit an explicit wall-clock deadline before finishing. Continue from Findings rather than redoing completed work; re-dispatch with continuation context and a longer deadline only if more wall-clock time is warranted.]";
 
-const THRASH_PARENT_HINT =
-  "[Sub-agent stopped for progressive thrash (re-read pressure). Do not re-dispatch the identical brief (it will be refused) — change scope, success_criteria, and do_not; continue from Findings.]";
-
 const NO_SHIP_PARENT_HINT =
   "[Sub-agent stopped after searching many files without writing any. Do not search the repo yourself and do not re-dispatch the identical brief (it will be refused) — change success_criteria and do_not, or treat findings as unexecuted.]";
 
@@ -611,11 +602,6 @@ export function appendDeadlineParentHint(report: string): string {
   return `${DEADLINE_PARENT_HINT}\n\n${report}`;
 }
 
-export function appendThrashParentHint(report: string): string {
-  if (!isThrashSubAgentReport(report)) return report;
-  return `${THRASH_PARENT_HINT}\n\n${report}`;
-}
-
 /** True when the worker returned a no-ship (search-tour) salvage report. */
 export function isNoShipSubAgentReport(report: string): boolean {
   const parsed = parseSubAgentReport(report);
@@ -643,7 +629,7 @@ export function appendNoProgressParentHint(report: string): string {
   return `${NO_PROGRESS_PARENT_HINT}\n\n${report}`;
 }
 
-/** Stack parent-visible salvage hints for thrash / budget / never-acted / deadline / repetition / no-progress. */
+/** Stack parent-visible salvage hints for budget / never-acted / deadline / repetition / no-progress. */
 export function appendSubAgentParentHints(
   report: string,
   options: SubAgentParentHintOptions = {},
@@ -652,9 +638,7 @@ export function appendSubAgentParentHints(
     appendNeverEditedParentHint(
       appendNeverActedParentHint(
         appendTurnBudgetParentHint(
-          appendNoProgressParentHint(
-            appendNoShipParentHint(appendThrashParentHint(appendRepetitionParentHint(report))),
-          ),
+          appendNoProgressParentHint(appendNoShipParentHint(appendRepetitionParentHint(report))),
           options,
         ),
       ),