fix: replace default compaction template to prevent purple italic rendering

Root cause: OpenCode's default compaction template uses --- separators.
When our plugin adds structured context (Memory candidates: format), the
model strictly follows the template, outputting --- at position 0. The
markdown textmate grammar treats this as YAML frontmatter, applying the
'comment' syntax scope (purple + italic in themes like palenight).

Fix: Set output.prompt in the compacting hook to replace the entire
template with a ---free version. Uses only ## Markdown headings and
explicitly forbids YAML frontmatter, horizontal rules, and delimiter
lines. Preserves context from other plugins by merging output.context.

- Replace compactionContextHeader() with buildCompactionPrompt()
- Set output.prompt instead of pushing to output.context
- Merge existing output.context from other plugins before clearing
- Add 'Instructions' section to the template (per architect review)
- Update tests: verify output.prompt, ---free format, context merging

docs/superpowers/plans/2026-04-26-memory-plugin-quality-fixes.md

@@ -982,12 +982,34 @@ for (const { text, expected } of QUALITY_GATE_TESTS) {
 ### 本週：PR-1
 
 1. Baseline snapshot
-2. Task 1: inline exitCode + 收窄 extractErrorsFromBash + **plugin hook regression test**
-3. Task 2: budget-aware render + **min envelope handling**
-4. Task 3: remove bare `always` + **ensure all patterns have `g` flag**
+2. Task 1: inline exitCode + 收窄 extractErrorsFromBash + **plugin hook regression test** ✅ DONE
+3. Task 2: budget-aware render + **min envelope handling** ✅ DONE
+4. Task 3: remove bare `always` + **ensure all patterns have `g` flag** ✅ DONE
 5. Manual verification
 6. Cleanup false positives
 
+### Hotfix: 紫色斜體渲染問題
+
+**問題**：Plugin compaction context 輸出在 OpenCode UI 中顯示為紫色斜體。
+
+**根因分析**：
+1. 第一次嘗試：XML 標籤 `<workspace_memory>` → 紫色斜體
+2. 第二次嘗試：HTML 註釋 `<!-- workspace_memory_candidates -->` → 仍然紫色斜體
+3. 第三次嘗試：Markdown 標題 `## Memory Candidates` → 紫色（無斜體）
+4. 第四次嘗試：純文本標籤 `Memory candidates:` → 無特殊渲染 ✅
+
+**解決方案**：架構師建議使用純文本標籤，避免所有 Markdown/XML/HTML 語法。
+
+**修改內容**：
+- `src/plugin.ts`: `compactionContextHeader()` 改用 `Memory candidates:` 標籤
+- `src/plugin.ts`: `renderTodosForCompaction()` 改用 `Pending todos:` 標籤
+- `src/extractors.ts`: `extractCandidateBlock()` 支援純文本格式解析（primary）
+- `src/workspace-memory.ts`: `renderWorkspaceMemory()` 使用純文本 `Workspace memory:` 標籤
+- `src/session-state.ts`: `renderHotSessionState()` 使用純文本 `Hot session state:` 標籤
+- 移除 `stripXmlTags()` 函數（不再需要）
+
+**測試**：42 個測試全部通過。
+
 ### 下週：PR-2
 
 5. Task 5: canonical exact dedupe + **source priority**

src/plugin.ts

@@ -46,28 +46,63 @@ import {
 } from "./opencode.ts";
 
 /**
- * Generate instructions for the compaction model.
+ * Build the complete compaction prompt.
+ *
+ * Replaces OpenCode's default template (which uses --- separators that trigger
+ * YAML frontmatter comment scope in markdown rendering, producing purple italic text).
+ * Our template uses only ## Markdown headings and explicitly forbids YAML frontmatter,
+ * horizontal rules, and delimiter lines.
+ *
+ * @param privateContext - Background context (workspace memory, hot session state,
+ *   pending todos) from our plugin and any other plugins. Shown to the model to
+ *   inform the summary but not copied verbatim.
  */
-function compactionContextHeader(): string {
-  return `
-Background context for memory extraction (do not output verbatim):
-- Use facts to update Goal/Progress/Key Decisions/Next Steps sections
-- At the end, emit durable future-session memories in this format:
-
-Memory candidates:
-- [feedback] content
-- [project] content
-- [decision] content
-- [reference] content
-`.trim();
-}
-
-/**
- * Generate the memory candidate instruction.
- * This is included in compactionContextHeader() above.
- */
-function memoryCandidateInstruction(): string {
-  return "";
+function buildCompactionPrompt(privateContext: string): string {
+  return [
+    "Provide a detailed summary for continuing our conversation above.",
+    "Focus on information that would help another agent continue the work: the goal, user instructions, completed work, current state, decisions, relevant files, and next steps.",
+    "",
+    "Do not call any tools. Respond only with the summary text.",
+    "Respond in the same language as the user's messages in the conversation.",
+    "",
+    "Formatting rules:",
+    "- Start the response with \"## Goal\".",
+    "- Use Markdown headings only.",
+    "- Do not output YAML frontmatter.",
+    "- Do not output horizontal rules.",
+    "- Do not wrap the summary in delimiter lines such as ---.",
+    "- Do not use code fences around the summary.",
+    "",
+    "Use this structure:",
+    "",
+    "## Goal",
+    "",
+    "## Instructions",
+    "",
+    "## Progress",
+    "",
+    "## Key Decisions",
+    "",
+    "## Discoveries",
+    "",
+    "## Next Steps",
+    "",
+    "## Relevant Files",
+    "",
+    "At the end of the summary, extract durable memory entries for future",
+    "sessions using these labels:",
+    "",
+    "Memory candidates:",
+    "- [feedback] content",
+    "- [project] content",
+    "- [decision] content",
+    "- [reference] content",
+    "",
+    "Background context, use this to inform the summary above.",
+    "Do not output this context verbatim:",
+    "",
+    privateContext,
+  ].join("\n");
 }
 
 /**
@@ -295,7 +330,17 @@ export const MemoryV2Plugin: Plugin = async (input) => {
       await processLatestUserMessage(sessionID);
     },
 
-    // Add compaction context before summarization
+    /**
+     * Replace the default compaction prompt with a ---free template.
+     *
+     * OpenCode's default template wraps sections in --- separators. When the
+     * model follows the template (which our structured context encourages),
+     * the TUI renders --- at position 0 as YAML frontmatter, applying the
+     * "comment" syntax scope (purple italic in palenight theme).
+     *
+     * We set output.prompt to replace the entire prompt, removing all ---
+     * and explicitly forbidding YAML frontmatter / horizontal rules.
+     */
     "experimental.session.compacting": async (hookInput, output) => {
       const { sessionID } = hookInput;
       if (!sessionID) return;
@@ -303,36 +348,47 @@ export const MemoryV2Plugin: Plugin = async (input) => {
       // Sub-agents don't need compaction support
       if (await isSubAgent(sessionID)) return;
 
-// Build private context with Markdown-neutral format
-const contextParts: string[] = [];
+      // Preserve context injected by other plugins that ran before us.
+      // Setting output.prompt bypasses the default prompt + context join,
+      // so we must explicitly carry forward any existing output.context.
+      const otherContext = output.context.filter(Boolean).join("\n\n");
 
-// 1. Frozen workspace memory
-const workspaceMemory = await getFrozenWorkspaceMemory(directory, sessionID);
-const workspacePrompt = renderWorkspaceMemory(workspaceMemory);
-if (workspacePrompt) {
-  contextParts.push(workspacePrompt);
-}
+      // Build our private context (workspace memory, hot state, todos)
+      const contextParts: string[] = [];
 
-// 2. Hot session state
-const sessionState = await loadSessionState(directory, sessionID);
-const hotPrompt = renderHotSessionState(sessionState, directory);
-if (hotPrompt) {
-  contextParts.push(hotPrompt);
-}
+      // 1. Frozen workspace memory
+      const workspaceMemory = await getFrozenWorkspaceMemory(directory, sessionID);
+      const workspacePrompt = renderWorkspaceMemory(workspaceMemory);
+      if (workspacePrompt) {
+        contextParts.push(workspacePrompt);
+      }
 
-      // 3. Pending todos from OpenCode (Markdown-neutral format)
+      // 2. Hot session state
+      const sessionState = await loadSessionState(directory, sessionID);
+      const hotPrompt = renderHotSessionState(sessionState, directory);
+      if (hotPrompt) {
+        contextParts.push(hotPrompt);
+      }
+
+      // 3. Pending todos from OpenCode
       const todos = await pendingTodos(client, sessionID);
       const todosPrompt = renderTodosForCompaction(todos);
       if (todosPrompt) {
         contextParts.push(todosPrompt);
       }
 
-      // Combine into single private context block
-      const privateContext = contextParts.length > 0
-        ? `${compactionContextHeader()}\n\n${contextParts.join("\n\n")}`
-        : compactionContextHeader();
+      // Combine: other plugins' context first, then our private context
+      const privateContext = [otherContext, ...contextParts]
+        .filter(Boolean)
+        .join("\n\n");
 
-      output.context.push(privateContext);
+      // Replace the default prompt entirely with our ---free template
+      output.prompt = buildCompactionPrompt(privateContext);
+
+      // Clear context array since we consumed it into output.prompt.
+      // Subsequent plugins that set output.prompt will also need to check
+      // output.context if they want to preserve other plugin contributions.
+      output.context.length = 0;
     },
 
     // Handle session events

tests/plugin.test.ts

@@ -195,7 +195,7 @@ test("tool.execute.after: exitCode non-zero creates open error", async () => {
   }
 });
 
-test("experimental.session.compacting: context contains no XML tags for compaction", async () => {
+test("compaction hook sets output.prompt with ---free template", async () => {
   const tmpDir = await mkdtemp(join(tmpdir(), "memory-plugin-test-"));
 
   try {
@@ -220,53 +220,75 @@ test("experimental.session.compacting: context contains no XML tags for compacti
       output
     );
 
-    // The context should be a single string (private context block)
-    assert.equal(output.context.length, 1, "Context should be a single block");
+    // Should set output.prompt and clear output.context
+    const prompt = (output as Record<string, unknown>).prompt as string | undefined;
+    assert.ok(prompt, "output.prompt should be set");
+    assert.equal(typeof prompt, "string", "output.prompt should be a string");
+    assert.equal(output.context.length, 0, "output.context should be cleared after setting prompt");
 
-    const contextText = output.context[0];
+    // Should NOT contain YAML frontmatter separators (--- at start)
+    assert.equal(prompt!.includes("\n---"), false,
+      "Prompt should not contain --- separators on their own line");
 
-    // Verify: context should NOT contain XML-like tags that confuse Markdown
-    assert.equal(contextText.includes("<workspace_memory>"), false,
-      "Context should not contain <workspace_memory> tag");
-    assert.equal(contextText.includes("</workspace_memory>"), false,
-      "Context should not contain </workspace_memory> tag");
-    assert.equal(contextText.includes("<hot_session_state>"), false,
-      "Context should not contain <hot_session_state> tag");
-    assert.equal(contextText.includes("<pending_todos>"), false,
-      "Context should not contain <pending_todos> tag");
+    // Should NOT contain XML-like tags
+    assert.equal(prompt!.includes("<workspace_memory>"), false);
+    assert.equal(prompt!.includes("</workspace_memory>"), false);
+    assert.equal(prompt!.includes("<hot_session_state>"), false);
+    assert.equal(prompt!.includes("<pending_todos>"), false);
 
-    // Verify: context should NOT contain square bracket markers
-    assert.equal(contextText.includes("[PRIVATE COMPACTION CONTEXT"), false,
-      "Context should not contain square bracket markers");
+    // Should NOT contain HTML comments
+    assert.equal(prompt!.includes("<!--"), false);
 
-    // Verify: context should contain plain text headers
-    assert.equal(contextText.includes("Workspace memory") || contextText.includes("Hot session state") || contextText.includes("Pending todos"), true,
-      "Context should use plain text headers instead of XML tags");
+    // Should contain the ---free template heading
+    assert.equal(prompt!.includes("## Goal"), true,
+      "Prompt should use ## Goal heading, not --- separators");
+
+    // Should contain formatting rules that explicitly forbid ---
+    assert.equal(prompt!.includes("Do not output YAML frontmatter"), true,
+      "Prompt should explicitly forbid YAML frontmatter");
+    assert.equal(prompt!.includes("horizontal rules"), true,
+      "Prompt should explicitly forbid horizontal rules");
+
+    // Should contain Memory candidates format
+    assert.equal(prompt!.includes("Memory candidates:"), true,
+      "Prompt should include Memory candidates: label");
+
+    // Should contain our context data (hot session state)
+    assert.equal(prompt!.includes("Hot session state"), true,
+      "Prompt should include hot session state context");
+
+    // Verify: prompt starts with plain text, not a markup delimiter
+    assert.equal(prompt!.startsWith("---"), false,
+      "Prompt should not start with --- (YAML frontmatter)");
+    assert.equal(prompt!.startsWith("##"), false,
+      "Prompt should start with plain instructions, not a heading");
 
   } finally {
     await rm(tmpDir, { recursive: true, force: true });
   }
 });
 
-test("compactionContextHeader does not require XML output", async () => {
+test("compaction hook merges existing output.context from other plugins", async () => {
   const tmpDir = await mkdtemp(join(tmpdir(), "memory-plugin-test-"));
 
   try {
     const client = mockRootClient();
     const plugin = await MemoryV2Plugin({ directory: tmpDir, client });
 
-    // Call the compaction hook to get the actual header
-    const output = { context: [] as string[] };
+    // Simulate another plugin having pushed context first
+    const output = { context: ["Other plugin context data"] };
     await (plugin as Record<string, Function>)["experimental.session.compacting"](
-      { sessionID: "test-header-session" },
+      { sessionID: "test-merge-context" },
       output
     );
 
-    const header = output.context[0] || "";
+    const prompt = (output as Record<string, unknown>).prompt as string | undefined;
+    assert.ok(prompt, "output.prompt should be set");
+    assert.equal(output.context.length, 0, "output.context should be cleared");
 
-    // Should instruct plain text label format (not Markdown headers)
-    assert.equal(header.includes("Memory candidates:"), true,
-      "Header should use plain text 'Memory candidates:' label");
+    // Should contain the other plugin's context
+    assert.equal(prompt!.includes("Other plugin context data"), true,
+      "Prompt should preserve context from other plugins");
 
   } finally {
     await rm(tmpDir, { recursive: true, force: true });