Enum ContentBlock 

pub enum ContentBlock {
    Text(TextBlock),
    ToolUse(ToolUseBlock),
    ToolResult(ToolResultBlock),
    Image(ImageBlock),
    Attachment(AttachmentBlock),
    Thinking(ThinkingBlock),
    Unknown,
}

Content block discriminator

All possible content block types found in message content arrays. Uses serde’s tagged enum to automatically parse based on type field.

Links

• User messages contain: Text, ToolResult, Image
• Assistant messages contain: Text, ToolUse, Thinking (when extended thinking enabled)
• Progress normalized messages contain: all types including Attachment

Frequency (per large session)

• ToolUse: ~30k occurrences
• ToolResult: ~30k occurrences
• Text: ~19k occurrences
• Thinking: Variable (only when extended thinking mode enabled)
• Image: ~5 occurrences

Variants

Text(TextBlock)

Text content block

Found in: user messages, assistant messages

Contains plain text or markdown from user input or assistant responses.

ToolUse(ToolUseBlock)

Tool use invocation

Found in: assistant messages

Represents Claude invoking a tool (Read, Write, Edit, Bash, etc.)

ToolResult(ToolResultBlock)

Tool execution result

Found in: user messages (as tool result feedback)

Contains the output from a tool execution, sent back to Claude.

Image(ImageBlock)

Image attachment

Found in: user messages

Base64-encoded image data sent by user.

Attachment(AttachmentBlock)

Attachment (files, hooks, reminders)

Found in: progress normalized messages

See attachment module for detailed attachment types.

Thinking(ThinkingBlock)

Thinking block (extended thinking mode)

Found in: assistant messages (only when user enables extended thinking)

Contains Claude’s reasoning process with signature verification. This is OPTIONAL - only present when extended thinking mode is enabled.

Unknown

Unknown content block type (forward compatibility)

Implementations

impl ContentBlock

pub fn as_text(&self) -> Option<&str>

Extract text if this is a text block

pub fn as_tool_use(&self) -> Option<(&str, &str, &JsonValue)>

Extract tool use if this is a tool use block

pub fn as_thinking(&self) -> Option<&str>

Extract thinking if this is a thinking block

pub fn is_tool_result(&self) -> bool

Check if this is a tool result

pub fn is_attachment(&self) -> bool

Check if this is an attachment

pub fn is_thinking(&self) -> bool

Check if this is a thinking block

Trait Implementations

impl Clone for ContentBlock

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ContentBlock

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for ContentBlock

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for ContentBlock

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.