fix: resolve 25 pre-publish blockers

- postinstall.mjs: fix alias package detection
- migrate-legacy-plugin-entry: dedupe + regression tests
- task_system: default consistency across runtime paths
- task() contract: consistent tool behavior
- runtime model selection, tool cap, stale-task cancellation
- recovery sanitization, context-limit gating
- Ralph semantic DONE hardening, Atlas fallback persistence
- native-skill description/content, skill path traversal guard
- publish workflow: platform awaited via reusable workflow job
- release: version edits reapplied before commit/tag
- JSONC plugin migration: top-level plugin key safety
- cold-cache: user fallback models skip disconnected providers
- docs/version/release framing updates

Verified: bun test (4599 pass), tsc --noEmit clean, bun run build clean

src/hooks/start-work/index.test.ts

@@ -12,7 +12,6 @@ import {
 import type { BoulderState } from "../../features/boulder-state"
 import * as sessionState from "../../features/claude-code-session-state"
 import * as worktreeDetector from "./worktree-detector"
-import * as worktreeDetector from "./worktree-detector"
 
 describe("start-work hook", () => {
   let testDir: string
@@ -26,6 +25,9 @@ describe("start-work hook", () => {
   }
 
   beforeEach(() => {
+    sessionState._resetForTesting()
+    sessionState.registerAgentName("atlas")
+    sessionState.registerAgentName("sisyphus")
     testDir = join(tmpdir(), `start-work-test-${randomUUID()}`)
     sisyphusDir = join(testDir, ".sisyphus")
     if (!existsSync(testDir)) {
@@ -38,6 +40,7 @@ describe("start-work hook", () => {
   })
 
   afterEach(() => {
+    sessionState._resetForTesting()
     clearBoulderState(testDir)
     if (existsSync(testDir)) {
       rmSync(testDir, { recursive: true, force: true })
@@ -409,7 +412,7 @@ describe("start-work hook", () => {
       // given
       const hook = createStartWorkHook(createMockPluginInput())
       const output = {
-        message: {},
+        message: {} as Record<string, unknown>,
         parts: [{ type: "text", text: "<session-context></session-context>" }],
       }
 
@@ -422,6 +425,29 @@ describe("start-work hook", () => {
       // then
       expect(output.message.agent).toBe("Atlas (Plan Executor)")
     })
+
+    test("should keep the current agent when Atlas is unavailable", async () => {
+      // given
+      sessionState._resetForTesting()
+      sessionState.registerAgentName("sisyphus")
+      sessionState.updateSessionAgent("ses-prometheus-to-sisyphus", "sisyphus")
+
+      const hook = createStartWorkHook(createMockPluginInput())
+      const output = {
+        message: {} as Record<string, unknown>,
+        parts: [{ type: "text", text: "<session-context></session-context>" }],
+      }
+
+      // when
+      await hook["chat.message"](
+        { sessionID: "ses-prometheus-to-sisyphus" },
+        output
+      )
+
+      // then
+      expect(output.message.agent).toBe("Sisyphus (Ultraworker)")
+      expect(sessionState.getSessionAgent("ses-prometheus-to-sisyphus")).toBe("sisyphus")
+    })
   })
 
   describe("worktree support", () => {

src/hooks/start-work/start-work-hook.ts

@@ -12,7 +12,7 @@ import {
 } from "../../features/boulder-state"
 import { log } from "../../shared/logger"
 import { getAgentDisplayName } from "../../shared/agent-display-names"
-import { updateSessionAgent, isAgentRegistered } from "../../features/claude-code-session-state"
+import { getSessionAgent, isAgentRegistered, updateSessionAgent } from "../../features/claude-code-session-state"
 import { detectWorktreePath } from "./worktree-detector"
 import { parseUserRequest } from "./parse-user-request"
 
@@ -80,14 +80,13 @@ export function createStartWorkHook(ctx: PluginInput) {
       if (!promptText.includes("<session-context>")) return
 
       log(`[${HOOK_NAME}] Processing start-work command`, { sessionID: input.sessionID })
-      const atlasDisplayName = getAgentDisplayName("atlas")
-      if (isAgentRegistered("atlas") || isAgentRegistered(atlasDisplayName)) {
-        updateSessionAgent(input.sessionID, "atlas")
-        if (output.message) {
-          output.message["agent"] = atlasDisplayName
-        }
-      } else {
-        log(`[${HOOK_NAME}] Atlas agent not available, continuing with current agent`, { sessionID: input.sessionID })
+      const activeAgent = isAgentRegistered("atlas")
+        ? "atlas"
+        : getSessionAgent(input.sessionID) ?? "sisyphus"
+      const activeAgentDisplayName = getAgentDisplayName(activeAgent)
+      updateSessionAgent(input.sessionID, activeAgent)
+      if (output.message) {
+        output.message["agent"] = activeAgentDisplayName
       }
 
       const existingState = readBoulderState(ctx.directory)
@@ -116,7 +115,7 @@ The requested plan "${getPlanName(matchedPlan)}" has been completed.
 All ${progress.total} tasks are done. Create a new plan with: /plan "your task"`
           } else {
             if (existingState) clearBoulderState(ctx.directory)
-            const newState = createBoulderState(matchedPlan, sessionId, "atlas", worktreePath)
+            const newState = createBoulderState(matchedPlan, sessionId, activeAgent, worktreePath)
             writeBoulderState(ctx.directory, newState)
 
             contextInfo = `
@@ -223,7 +222,7 @@ All ${plans.length} plan(s) are complete. Create a new plan with: /plan "your ta
         } else if (incompletePlans.length === 1) {
           const planPath = incompletePlans[0]
           const progress = getPlanProgress(planPath)
-          const newState = createBoulderState(planPath, sessionId, "atlas", worktreePath)
+          const newState = createBoulderState(planPath, sessionId, activeAgent, worktreePath)
           writeBoulderState(ctx.directory, newState)
 
           contextInfo += `