chore: import upstream snapshot with attribution

docs/python/resource/ram.mdx

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+---
+title: RAM
+description: Use an in-memory Mirage filesystem for temporary files, tests, examples, and writable agent scratch space.
+icon: memory
+---
+The RAM resource exposes an in-memory filesystem mounted at some prefix
+such as `/data/`. All data lives in process memory and is lost on exit.
+
+No setup or credentials required.
+
+## Config
+
+```python
+from mirage import MountMode, Workspace
+from mirage.resource.ram import RAMResource
+
+resource = RAMResource()
+ws = Workspace({"/data": resource}, mode=MountMode.WRITE)
+```
+
+No configuration object needed - `RAMResource()` takes no arguments.
+
+## Filesystem Layout
+
+The RAM filesystem starts empty. Files and directories are created
+on demand via commands like `touch`, `mkdir`, `tee`, `cp`, etc.
+
+```text
+/data/
+  notes.txt
+  config.json
+  reports/
+    q1.csv
+    q2.csv
+  uploads/
+    image.png
+```
+
+Paths are normalized with a leading `/`. The root directory `/` always
+exists.
+
+## Cache
+
+The RAM resource uses `IndexCacheStore` with `index_ttl = 0` (no
+expiry). Since all data is in-memory, the index is always fresh,
+no network calls or stale cache concerns.
+
+## Example
+
+```python
+import asyncio
+
+from mirage import MountMode, Workspace
+from mirage.resource.ram import RAMResource
+
+resource = RAMResource()
+
+
+async def main() -> None:
+    ws = Workspace({"/data": resource}, mode=MountMode.WRITE)
+
+    # Create files
+    await ws.execute('echo "hello world" | tee /data/hello.txt')
+    await ws.execute('echo \'{"name": "alice", "age": 30}\' | tee /data/user.json')
+    await ws.execute("mkdir /data/reports")
+    await ws.execute('echo "revenue,100" | tee /data/reports/q1.csv')
+
+    # Read
+    r = await ws.execute("cat /data/hello.txt")
+    print(await r.stdout_str())
+
+    # List
+    r = await ws.execute("ls /data/")
+    print(await r.stdout_str())
+
+    # Query JSON
+    r = await ws.execute('jq ".name" /data/user.json')
+    print(await r.stdout_str())
+
+    # Search
+    r = await ws.execute("grep hello /data/hello.txt")
+    print(await r.stdout_str())
+
+    # Tree
+    r = await ws.execute("tree /data/")
+    print(await r.stdout_str())
+
+    # File info
+    r = await ws.execute("stat /data/hello.txt")
+    print(await r.stdout_str())
+
+    # Copy, move, remove
+    await ws.execute("cp /data/hello.txt /data/hello_copy.txt")
+    await ws.execute("mv /data/hello_copy.txt /data/renamed.txt")
+    await ws.execute("rm /data/renamed.txt")
+
+
+if __name__ == "__main__":
+    asyncio.run(main())
+```
+
+## Shell Commands
+
+The RAM resource supports the full set of shell commands since it
+handles real file content (text, binary, JSON, CSV, etc.):
+
+### Read Commands
+
+| Command         | Notes                                      |
+| --------------- | ------------------------------------------ |
+| `cat`           | Read file content                          |
+| `head` / `tail` | First/last N lines                         |
+| `grep` / `rg`   | Pattern search (file or directory level)   |
+| `jq`            | Query JSON fields                          |
+| `wc`            | Line/word/byte counts                      |
+| `stat`          | File metadata (name, size, type, modified) |
+| `find`          | Recursive search with `-name`, `-maxdepth` |
+| `tree`          | Directory tree view                        |
+| `nl`            | Number lines                               |
+| `du`            | Disk usage summary                         |
+| `file`          | Detect file type                           |
+| `strings`       | Extract printable strings from binary      |
+| `xxd`           | Hex dump                                   |
+| `md5`           | MD5 checksum                               |
+| `sha256sum`     | SHA-256 checksum                           |
+
+### Text Processing
+
+| Command    | Notes                                       |
+| ---------- | ------------------------------------------- |
+| `awk`      | Pattern scanning and processing             |
+| `sed`      | Stream editor                               |
+| `tr`       | Translate or delete characters              |
+| `sort`     | Sort lines                                  |
+| `uniq`     | Remove duplicate lines                      |
+| `cut`      | Extract fields/columns                      |
+| `join`     | Join lines on a common field                |
+| `paste`    | Merge lines side by side                    |
+| `column`   | Columnate output                            |
+| `fold`     | Wrap lines to a specified width             |
+| `expand`   | Convert tabs to spaces                      |
+| `unexpand` | Convert spaces to tabs                      |
+| `fmt`      | Simple text formatter                       |
+| `rev`      | Reverse lines                               |
+| `tac`      | Concatenate and print in reverse            |
+| `look`     | Display lines beginning with a given string |
+| `shuf`     | Shuffle lines                               |
+| `tsort`    | Topological sort                            |
+| `comm`     | Compare two sorted files                    |
+| `cmp`      | Compare two files byte by byte              |
+| `diff`     | Compare files line by line                  |
+| `patch`    | Apply a diff patch                          |
+| `iconv`    | Character encoding conversion               |
+
+### File Operations
+
+| Command  | Notes                                 |
+| -------- | ------------------------------------- |
+| `cp`     | Copy files                            |
+| `mv`     | Move/rename files                     |
+| `rm`     | Remove files                          |
+| `mkdir`  | Create directories                    |
+| `touch`  | Create empty file or update timestamp |
+| `ln`     | Create symbolic links                 |
+| `tee`    | Write stdin to file and stdout        |
+| `mktemp` | Create temporary file                 |
+| `split`  | Split file into pieces                |
+| `csplit` | Split file by context                 |
+
+### Path Utilities
+
+| Command    | Notes                      |
+| ---------- | -------------------------- |
+| `basename` | Strip directory from path  |
+| `dirname`  | Strip filename from path   |
+| `realpath` | Resolve path               |
+| `readlink` | Print symbolic link target |
+| `ls`       | List directory contents    |
+
+### Compression
+
+| Command  | Notes                 |
+| -------- | --------------------- |
+| `gzip`   | Compress files        |
+| `gunzip` | Decompress gzip files |
+| `zip`    | Create zip archives   |
+| `unzip`  | Extract zip archives  |
+| `tar`    | Archive files         |
+| `zcat`   | Cat compressed files  |
+| `zgrep`  | Grep compressed files |
+
+### Encoding
+
+| Command  | Notes                |
+| -------- | -------------------- |
+| `base64` | Base64 encode/decode |
+
+### Data Format Support
+
+Commands with format-specific variants for structured data files:
+
+| Format  | Extension  | Variants                                       |
+| ------- | ---------- | ---------------------------------------------- |
+| Parquet | `.parquet` | cat, head, tail, wc, stat, cut, grep, ls, file |
+| Feather | `.feather` | cat, head, tail, wc, stat, cut, grep, ls, file |
+| ORC     | `.orc`     | cat, head, tail, wc, stat, cut, grep, ls, file |
+| HDF5    | `.hdf5`    | cat, head, tail, wc, stat, cut, grep, ls, file |
+
+These variants auto-detect the format by extension and convert to
+tabular text (CSV) for processing.
+
+## Use Cases
+
+- **Testing**: Fast filesystem for unit tests without I/O
+- **Staging**: Temporary data area during pipelines
+- **Prototyping**: Develop against a filesystem before switching to S3/disk
+- **Caching**: In-process data exchange between commands
+- **Ephemeral workspaces**: Create, process, discard - no cleanup needed