diff --git a/src/hooks/ralph-loop/completion-promise-detector.test.ts b/src/hooks/ralph-loop/completion-promise-detector.test.ts
index b63640457..bbb2206fb 100644
--- a/src/hooks/ralph-loop/completion-promise-detector.test.ts
+++ b/src/hooks/ralph-loop/completion-promise-detector.test.ts
@@ -1,7 +1,7 @@
 /// <reference types="bun-types" />
 import { describe, expect, test } from "bun:test"
 import type { PluginInput } from "@opencode-ai/plugin"
-import { detectCompletionInSessionMessages } from "./completion-promise-detector"
+import { detectCompletionInSessionMessages, detectSemanticCompletion } from "./completion-promise-detector"
 
 type SessionMessage = {
   info?: { role?: string }
@@ -184,4 +184,148 @@ describe("detectCompletionInSessionMessages", () => {
       expect(detected).toBe(false)
     })
   })
+
+  describe("#given semantic completion patterns", () => {
+    test("#when agent says 'task is complete' #then should detect semantic completion", async () => {
+      // #given
+      const messages: SessionMessage[] = [
+        {
+          info: { role: "assistant" },
+          parts: [{ type: "text", text: "The task is complete. All work has been finished." }],
+        },
+      ]
+      const ctx = createPluginInput(messages)
+
+      // #when
+      const detected = await detectCompletionInSessionMessages(ctx, {
+        sessionID: "session-123",
+        promise: "DONE",
+        apiTimeoutMs: 1000,
+        directory: "/tmp",
+      })
+
+      // #then
+      expect(detected).toBe(true)
+    })
+
+    test("#when agent says 'all items are done' #then should detect semantic completion", async () => {
+      // #given
+      const messages: SessionMessage[] = [
+        {
+          info: { role: "assistant" },
+          parts: [{ type: "text", text: "All items are done and marked as complete." }],
+        },
+      ]
+      const ctx = createPluginInput(messages)
+
+      // #when
+      const detected = await detectCompletionInSessionMessages(ctx, {
+        sessionID: "session-123",
+        promise: "DONE",
+        apiTimeoutMs: 1000,
+        directory: "/tmp",
+      })
+
+      // #then
+      expect(detected).toBe(true)
+    })
+
+    test("#when agent says 'nothing left to do' #then should detect semantic completion", async () => {
+      // #given
+      const messages: SessionMessage[] = [
+        {
+          info: { role: "assistant" },
+          parts: [{ type: "text", text: "There is nothing left to do. Everything is finished." }],
+        },
+      ]
+      const ctx = createPluginInput(messages)
+
+      // #when
+      const detected = await detectCompletionInSessionMessages(ctx, {
+        sessionID: "session-123",
+        promise: "DONE",
+        apiTimeoutMs: 1000,
+        directory: "/tmp",
+      })
+
+      // #then
+      expect(detected).toBe(true)
+    })
+
+    test("#when agent says 'successfully completed all' #then should detect semantic completion", async () => {
+      // #given
+      const messages: SessionMessage[] = [
+        {
+          info: { role: "assistant" },
+          parts: [{ type: "text", text: "I have successfully completed all the required tasks." }],
+        },
+      ]
+      const ctx = createPluginInput(messages)
+
+      // #when
+      const detected = await detectCompletionInSessionMessages(ctx, {
+        sessionID: "session-123",
+        promise: "DONE",
+        apiTimeoutMs: 1000,
+        directory: "/tmp",
+      })
+
+      // #then
+      expect(detected).toBe(true)
+    })
+
+    test("#when promise is VERIFIED #then semantic completion should NOT trigger", async () => {
+      // #given
+      const messages: SessionMessage[] = [
+        {
+          info: { role: "assistant" },
+          parts: [{ type: "text", text: "The task is complete. All work has been finished." }],
+        },
+      ]
+      const ctx = createPluginInput(messages)
+
+      // #when
+      const detected = await detectCompletionInSessionMessages(ctx, {
+        sessionID: "session-123",
+        promise: "VERIFIED",
+        apiTimeoutMs: 1000,
+        directory: "/tmp",
+      })
+
+      // #then
+      expect(detected).toBe(false)
+    })
+  })
+})
+
+describe("detectSemanticCompletion", () => {
+  describe("#given semantic completion patterns", () => {
+    test("#when text contains 'task is complete' #then should return true", () => {
+      expect(detectSemanticCompletion("The task is complete.")).toBe(true)
+    })
+
+    test("#when text contains 'all items are done' #then should return true", () => {
+      expect(detectSemanticCompletion("All items are done.")).toBe(true)
+    })
+
+    test("#when text contains 'nothing left to do' #then should return true", () => {
+      expect(detectSemanticCompletion("There is nothing left to do.")).toBe(true)
+    })
+
+    test("#when text contains 'successfully completed all' #then should return true", () => {
+      expect(detectSemanticCompletion("Successfully completed all tasks.")).toBe(true)
+    })
+
+    test("#when text contains 'everything is finished' #then should return true", () => {
+      expect(detectSemanticCompletion("Everything is finished.")).toBe(true)
+    })
+
+    test("#when text does NOT contain completion patterns #then should return false", () => {
+      expect(detectSemanticCompletion("Working on the next task.")).toBe(false)
+    })
+
+    test("#when text is empty #then should return false", () => {
+      expect(detectSemanticCompletion("")).toBe(false)
+    })
+  })
 })
diff --git a/src/hooks/ralph-loop/completion-promise-detector.ts b/src/hooks/ralph-loop/completion-promise-detector.ts
index 40e9e1af7..57b85ca9c 100644
--- a/src/hooks/ralph-loop/completion-promise-detector.ts
+++ b/src/hooks/ralph-loop/completion-promise-detector.ts
@@ -9,6 +9,20 @@ interface OpenCodeSessionMessage {
 	parts?: Array<{ type: string; text?: string }>
 }
 
+interface TranscriptEntry {
+	type?: string
+	timestamp?: string
+	content?: string
+	tool_output?: { output?: string } | string
+}
+
+function extractTranscriptEntryText(entry: TranscriptEntry): string {
+	if (typeof entry.content === "string") return entry.content
+	if (typeof entry.tool_output === "string") return entry.tool_output
+	if (entry.tool_output && typeof entry.tool_output === "object" && typeof entry.tool_output.output === "string") return entry.tool_output.output
+	return ""
+}
+
 function escapeRegex(str: string): string {
 	return str.replace(/[.*+?^${}()|[\]\\]/g, "\\$&")
 }
@@ -17,6 +31,18 @@ function buildPromisePattern(promise: string): RegExp {
 	return new RegExp(`<promise>\\s*${escapeRegex(promise)}\\s*</promise>`, "is")
 }
 
+const SEMANTIC_COMPLETION_PATTERNS = [
+	/\b(?:task|work|implementation|all\s+tasks?)\s+(?:is|are)\s+(?:complete|completed|done|finished)\b/i,
+	/\ball\s+(?:items?|todos?|steps?)\s+(?:are\s+)?(?:complete|completed|done|finished|marked)\b/i,
+	/\b(?:everything|all\s+work)\s+(?:is\s+)?(?:complete|completed|done|finished)\b/i,
+	/\bsuccessfully\s+completed?\s+all\b/i,
+	/\bnothing\s+(?:left|more|remaining)\s+to\s+(?:do|implement|fix)\b/i,
+]
+
+export function detectSemanticCompletion(text: string): boolean {
+	return SEMANTIC_COMPLETION_PATTERNS.some((pattern) => pattern.test(text))
+}
+
 export function detectCompletionInTranscript(
 	transcriptPath: string | undefined,
 	promise: string,
@@ -33,10 +59,18 @@ export function detectCompletionInTranscript(
 
 		for (const line of lines) {
 			try {
-				const entry = JSON.parse(line) as { type?: string; timestamp?: string }
+				const entry = JSON.parse(line) as TranscriptEntry
 				if (entry.type === "user") continue
 				if (startedAt && entry.timestamp && entry.timestamp < startedAt) continue
-				if (pattern.test(line)) return true
+				const entryText = extractTranscriptEntryText(entry)
+				if (!entryText) continue
+				if (pattern.test(entryText)) return true
+				// Fallback: semantic completion only for DONE promise and assistant entries
+				const isAssistantEntry = entry.type === "assistant" || entry.type === "text"
+				if (promise === "DONE" && isAssistantEntry && detectSemanticCompletion(entryText)) {
+					log("[ralph-loop] WARNING: Semantic completion detected in transcript (agent used natural language instead of <promise>DONE</promise>)")
+					return true
+				}
 			} catch {
 				continue
 			}
@@ -100,6 +134,14 @@ export async function detectCompletionInSessionMessages(
 			if (pattern.test(responseText)) {
 				return true
 			}
+
+			// Fallback: semantic completion only for DONE promise
+			if (options.promise === "DONE" && detectSemanticCompletion(responseText)) {
+				log("[ralph-loop] WARNING: Semantic completion detected (agent used natural language instead of <promise>DONE</promise>)", {
+					sessionID: options.sessionID,
+				})
+				return true
+			}
 		}
 
 		return false