# im +messages-reply

> **Prerequisite:** Read [`../lark-shared/SKILL.md`](../../lark-shared/SKILL.md) first to understand authentication, global parameters, and safety rules.

Reply to a specific message. Supports both user identity (`--as user`) and bot identity (`--as bot`). Also supports thread replies.

This skill maps to the shortcut: `lark-cli im +messages-reply` (internally calls `POST /open-apis/im/v1/messages/:message_id/reply`).

## Safety Constraints

Replies sent by this tool are visible to other people. Before calling it, you **must** confirm with the user:

1. Which message to reply to
2. The reply content
3. Which identity to use (user or bot)

**Do not** send a reply without explicit user approval.

When using `--as bot`, the reply is sent in the app's name, so make sure the app has already been added to the target chat.

When using `--as user`, the reply is sent as the authorized end user and requires the `im:message.send_as_user` and `im:message` scopes.

## Choose The Right Content Flag

### Default Selection Rule For Agents

- Prefer `--markdown` for headings, lists, links, summaries, investigation notes, or Markdown-looking content.
- Use `--text` for exact plain text: logs, code, indentation-sensitive text, or literal Markdown.
- Use `--content` for exact `post` JSON, titles, multiple locales, cards, or unsupported structures.

| Need | Recommended flag | Why |
|------|------|------|
| Reply with headings, lists, links, summaries, or investigation notes | `--markdown` | Best default for lightweight formatting; converted to Feishu `post` JSON |
| Reply with plain text exactly as written | `--text` | Preserves literal text; no Markdown conversion |
| Precisely control the reply payload | `--content` | You provide the exact JSON |
| Reply with media | `--image` / `--file` / `--video` / `--audio` | Shortcut uploads URLs, or cwd-relative local files automatically |

### `--text` vs `--markdown`

- Use `--markdown` for lightweight formatted replies.
- Use `--text` for exact plain text, especially logs, code, indentation, or literal Markdown characters.
- Use `--content` when you need exact `post` JSON, a card, a title, multiple locales, or any structure that `--markdown` cannot express reliably.

## What `--markdown` Really Does

`--markdown` accepts Markdown-like input and converts it to the Feishu `post` payload required by the reply API.

The shortcut:

1. Forces `msg_type=post`
2. Resolves remote Markdown images like `![x](https://...)`
3. Normalizes the Markdown for Feishu post rendering
4. Wraps the final content as:

```json
{"zh_cn":{"content":[[{"tag":"md","text":"..."}]]}}
```

This makes `--markdown` the simplest path for lightweight formatted replies.

### Markdown Boundaries

- It does **not** promise full CommonMark / GitHub Flavored Markdown support.
- It always becomes a `post` payload with a single `zh_cn` locale.
- It does **not** let you set a `post` title.
- Headings are rewritten:
    - `# Title` becomes `#### Title`
    - `##` to `######` are normalized to `#####` when the content contains H1-H3
- Consecutive headings are separated with blank lines after heading normalization.
- Block spacing and line breaks may be normalized during conversion.
- Code blocks are preserved as code blocks.
- Excess blank lines are compressed.
- Already-uploaded `img_xxx` image keys are the most reliable Markdown image input.
- Local paths (e.g. `![x](./a.png)`) are **not** supported directly in `--markdown` and will not be auto-uploaded.
- Remote URLs (`https://...`) will be auto-downloaded and uploaded at runtime; if the download or upload fails, the image is removed with a warning.

If you need a title, multiple locales, cards, unsupported rich structures, or byte-for-byte post JSON control, use `--msg-type post --content ...`.

### Image Constraint for `--markdown`

When using `--markdown` with images, prefer pre-uploading via `images.create` and referencing `![alt](img_xxx)` for predictable results. Remote URLs may work but are not guaranteed.

**Steps:**

```bash
# 1. Upload image to get image_key
lark-cli im images create --data '{"image_type":"message"}' --file ./diagram.png
# Returns: {"image_key":"img_v3_xxxx"}

# 2. Use image_key in --markdown reply
lark-cli im +messages-reply --message-id om_xxx --markdown $'## Result\n\n![diagram](img_v3_xxxx)\n\nSee above for details.'
```

## Preserving Formatting

If the reply contains multiple lines, code blocks, indentation, tabs, or a lot of escaping, prefer `$'...'` for either `--markdown` or `--text`.

### When formatting must be preserved

Use `--text` plus `$'...'`:

```bash
lark-cli im +messages-reply --message-id om_xxx --text $'Received\nI will check this today.\nOwner: alice'
```

```bash
lark-cli im +messages-reply --message-id om_xxx --text $'```sql\nselect * from jobs;\n```'
```

This keeps the reply as plain text instead of converting it to a `post`.

## Commands

```bash
# Reply with a formatted update
lark-cli im +messages-reply --message-id om_xxx --markdown $'## Reply\n\n- item 1\n- item 2'

# Reply with a plain one-line message
lark-cli im +messages-reply --message-id om_xxx --text "Received"

# Equivalent manual JSON
lark-cli im +messages-reply --message-id om_xxx --content '{"text":"Received"}'

# Reply as a bot
lark-cli im +messages-reply --message-id om_xxx --text "bot reply" --as bot

# Reply with preserved multi-line text
lark-cli im +messages-reply --message-id om_xxx --text $'Line 1\nLine 2\n  indented line'

# Reply inside the thread (message appears in the target thread)
lark-cli im +messages-reply --message-id om_xxx --text "Let's discuss this" --reply-in-thread

# Reply with Markdown containing an image (must pre-upload via images.create)
lark-cli im images create --data '{"image_type":"message"}' --file ./screenshot.png
# Use the returned image_key
lark-cli im +messages-reply --message-id om_xxx --markdown $'## Screenshot\n\n![screenshot](img_v3_xxxx)\n\nConfirmed.'

# If you need exact post structure, send JSON directly
lark-cli im +messages-reply --message-id om_xxx --msg-type post --content '{"zh_cn":{"title":"Reply","content":[[{"tag":"text","text":"Detailed content"}]]}}'

# Reply with a local image (uploaded automatically before sending)
lark-cli im +messages-reply --message-id om_xxx --image ./photo.png

# Reply with a local file (uploaded automatically before sending)
lark-cli im +messages-reply --message-id om_xxx --file ./report.pdf

# Reply with a local video (--video-cover is required as the video cover)
lark-cli im +messages-reply --message-id om_xxx --video ./demo.mp4 --video-cover ./cover.png

# Reply with a voice message
lark-cli im +messages-reply --message-id om_xxx --audio ./voice.opus

# With an idempotency key
lark-cli im +messages-reply --message-id om_xxx --text "Received" --idempotency-key my-unique-id

# Preview the request without executing it
lark-cli im +messages-reply --message-id om_xxx --markdown $'## Test\n\nhello' --dry-run
```

## Media Input Rules

- Media flags accept an existing key (`img_xxx` / `file_xxx`), an `http://` or `https://` URL, or a local file path.
- Local paths must be relative to the current working directory and stay within it after resolving `..` and symlinks.
- Absolute paths such as `/tmp/photo.png` are rejected. Run the command from the file's directory and pass `./photo.png`, or copy the file into the current directory first.
- `--audio` sends a voice message and accepts only Opus audio (`.opus` or Ogg Opus `.ogg`) for local paths and URLs. For `mp3`, `wav`, or other non-Opus audio, convert to `.opus` before using `--audio`, or use `--file` to send the original audio as an attachment.

## Parameters

| Parameter | Required | Description                                                                                                                                                                                   |
|------|------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `--message-id <id>` | Yes | ID of the message being replied to (`om_xxx`)                                                                                                                                                 |
| `--msg-type <type>` | No | Message type (default `text`). If you use `--text` / `--markdown` / media flags, the effective type is inferred automatically. Explicitly setting a conflicting `--msg-type` fails validation |
| `--content <json>` | One content option | Exact reply content as JSON. The JSON must match the effective `--msg-type`                                                                                                                   |
| `--text <string>` | One content option | Plain text reply. Use when exact text and formatting preservation matter                                                                                                                      |
| `--markdown <string>` | One content option | Best default for lightweight formatted replies such as headings, lists, links, summaries, and investigation notes. Internally converted to `post` JSON with Feishu-specific normalization |
| `--image <path\|url\|key>` | One content option | Cwd-relative local image path, URL, or `image_key` (`img_xxx`)                                                                                                                                |
| `--file <path\|url\|key>` | One content option | Cwd-relative local file path, URL, or `file_key` (`file_xxx`)                                                                                                                                 |
| `--video <path\|url\|key>` | One content option | Cwd-relative local video path, URL, or `file_key` (`file_xxx`); **must be used together with `--video-cover`**                                                                                |
| `--video-cover <path\|url\|key>` | **Required with `--video`** | Cwd-relative local cover image path, URL, or `image_key` (`img_xxx`)                                                                                                                          |
| `--audio <path\|url\|key>` | One content option | Voice-message audio key, URL, or cwd-relative local path. Local paths and URLs must be Opus (`.opus` or Ogg Opus `.ogg`) |
| `--reply-in-thread` | No | Reply inside the thread. The reply appears in the target message's thread instead of the main chat stream                                                                                     |
| `--idempotency-key <key>` | No | Idempotency key; the same key sends only one reply within 1 hour                                                                                                                              |
| `--as <identity>` | No | Identity type: `bot` or `user` (default `bot`)                                                                                                                                                |
| `--dry-run` | No | Print the request only, do not execute it                                                                                                                                                     |

> **Mutual exclusivity rule:** `--text`, `--markdown`, `--content`, and `--image`/`--file`/`--video`/`--audio` cannot be used together. Media flags are also mutually exclusive with each other.
>
> **Video cover rule:** `--video` **must** be accompanied by `--video-cover`. Omitting `--video-cover` when using `--video` will fail validation. `--video-cover` cannot be used without `--video`.

## Common Mistakes

- Choosing `--text` for headings, lists, links, summaries, or investigation notes. Use `--markdown`.
- Choosing `--markdown` when you actually need exact plain text. If exact line breaks, spacing, logs, code, or literal Markdown characters matter, use `--text`, usually with `$'...'`.
- Assuming `--markdown` supports every Markdown feature. It is converted into a Feishu `post` payload and normalized first.
- Putting local image paths inside Markdown like `![x](./a.png)`. `--markdown` does not auto-upload those paths.
- **Using local file paths inside Markdown image syntax** (e.g. `![x](./a.png)`) with `--markdown`. Local paths are not auto-uploaded and will not render as an image. Pre-upload via `images.create` to get an `image_key` instead.
- Using `--content` without making the JSON match the effective `--msg-type`.
- Explicitly setting `--msg-type` to something that conflicts with `--text`, `--markdown`, or media flags.
- Mixing `--text`, `--markdown`, or `--content` with media flags in one command.

## Return Value

```json
{
  "message_id": "om_xxx",
  "chat_id": "oc_xxx",
  "create_time": "1234567890"
}
```

## Usage Scenarios

### Scenario 1: Reply in the main chat stream

```bash
lark-cli im +messages-reply --message-id om_xxx --text "OK, I will handle it"
```

The reply appears in the main chat stream and references the target message.

### Scenario 2: Reply inside a thread

```bash
lark-cli im +messages-reply --message-id om_xxx --text "Let me take a look at this" --reply-in-thread
```

The reply appears in the target message's thread and does not show up in the main chat stream.

## @Mention Format

The `<at>` syntax differs by message type. The shortcut only normalizes mentions for `text` and `post`; `interactive` card content is passed through verbatim, so cards must use the card-native syntax below.

### `text`

- `<at user_id="ou_xxx">name</at>` — the inner text is the mentioned user's display name and is optional (`<at user_id="ou_xxx"></at>` also works)
- @all: `<at user_id="all"></at>`

### `post`

- Inside a `text` or `md` element, the same inline form as `text` works: `<at user_id="ou_xxx">name</at>`
- Or use a dedicated `at` element node: `{"tag":"at","user_id":"ou_xxx"}` (use `"all"` to mention everyone)

### `interactive` (card)

Card content is **not** normalized — use the card-native `<at>` syntax inside a `lark_md` / `markdown` element:

- single user by open_id: `<at id=ou_xxx></at>`
- multiple users: `<at ids=ou_xxx1,ou_xxx2></at>`
- by email: `<at email=user@example.com></at>`

## Notes

- `--message-id` must be a valid message ID in `om_xxx` format
- `--content` must be valid JSON
- When using `--content`, you are responsible for making the JSON structure match the effective `msg_type`
- `--reply-in-thread` adds `reply_in_thread=true` to the API request
- `--reply-in-thread` is mainly meaningful in chats that support thread replies
- `--image`/`--file`/`--video`/`--audio`/`--video-cover` support existing keys, URLs, and cwd-relative local file paths; the shortcut uploads local paths and URLs first, then sends the reply; both the upload and send steps use the same identity (UAT when `--as user`, TAT when `--as bot`)
- If the provided media value starts with `img_` or `file_`, it is treated as an existing key and used directly
- `--markdown` always sends `msg_type=post`
- If you explicitly set `--msg-type` and it conflicts with the chosen content flag, validation fails
- When using `--video`, `--video-cover` is required as the video cover
- `--dry-run` uses placeholder image keys for remote Markdown images and placeholder media keys for local uploads
- Failures return error codes and messages
- `--as user` uses a user access token (UAT) and requires the `im:message.send_as_user` and `im:message` scopes; the reply is sent as the authorized end user
- `--as bot` uses a tenant access token (TAT), and requires the `im:message:send_as_bot` scope
- When using `--markdown` with images, pre-uploading via `images.create` to obtain an `image_key` is recommended for reliability; remote URLs may be auto-resolved at runtime, but if download/upload fails the image is removed with a warning; local paths are not supported
