docs(agents): update hook counts 44→46, add hashline-edit documentation

- Update root AGENTS.md: hook count 44→46, commit fcb90d92, generated 2026-02-24
- Update src/AGENTS.md: core hooks 35→37, session hooks 21→23
- Update src/hooks/AGENTS.md: 46 hooks total, add modelFallback/noSisyphusGpt/noHephaestusNonGpt/runtimeFallback, jsonErrorRecovery moved to tool-guard (tier 2)
- Create src/tools/hashline-edit/AGENTS.md (93 lines): documents three-op model, LINE#ID format, execution pipeline
- Refresh timestamps: 2026-02-21→2026-02-24 on 28 files
- Update plugin/AGENTS.md hook composition counts

🤖 Generated with assistance of [OhMyOpenCode](https://github.com/code-yeongyu/oh-my-opencode)

.issue-comment-2064.md

@@ -0,0 +1,61 @@
+[sisyphus-bot] 
+
+## Confirmed Bug
+
+We have identified the root cause of this issue. The bug is in the config writing logic during installation.
+
+### Root Cause
+
+**File:** `src/cli/config-manager/write-omo-config.ts` (line 46)
+
+```typescript
+const merged = deepMergeRecord(existing, newConfig)
+```
+
+When a user runs `oh-my-opencode install` (even just to update settings), the installer:
+1. Reads the existing config (with user's custom model settings)
+2. Generates a **new** config based on detected provider availability
+3. Calls `deepMergeRecord(existing, newConfig)` 
+4. Writes the result back
+
+**The problem:** `deepMergeRecord` overwrites values in `existing` with values from `newConfig`. This means your custom `"model": "openai/gpt-5.2-codex"` gets overwritten by the generated default model (e.g., `anthropic/claude-opus-4-6` if Claude is available).
+
+### Why This Happens
+
+Looking at `deepMergeRecord` (line 24-25):
+```typescript
+} else if (sourceValue !== undefined) {
+  result[key] = sourceValue as TTarget[keyof TTarget]
+}
+```
+
+Any defined value in the source (generated config) overwrites the target (user's config).
+
+### Fix Approach
+
+The merge direction should be reversed to respect user overrides:
+```typescript
+const merged = deepMergeRecord(newConfig, existing)
+```
+
+This ensures:
+- User's explicit settings take precedence
+- Only new/undefined keys get populated from generated defaults
+- Custom model choices are preserved
+
+### SEVERITY: HIGH
+
+- **Impact:** User configuration is overwritten without consent
+- **Affected Files:** 
+  - `src/cli/config-manager/write-omo-config.ts`
+  - `src/cli/config-manager/deep-merge-record.ts`
+- **Trigger:** Running `oh-my-opencode install` (even for unrelated updates)
+
+### Workaround (Until Fix)
+
+Backup your config before running install:
+```bash
+cp ~/.config/opencode/oh-my-opencode.jsonc ~/.config/opencode/oh-my-opencode.jsonc.backup
+```
+
+We're working on a fix that will preserve your explicit model configurations.