Struct WriteContext 

pub struct WriteContext<W: Write> {
    pub writer: W,
    pub current_state: Value,
    pub observation_count: usize,
    pub snapshot_interval: Option<usize>,
    pub finish_strategy: FinishStrategy,
    pub diagnostics: DiagnosticCollector,
}

Context for writing observations to an archive.

This struct is the result of the “setup phase” for both create and append operations. Once you have a WriteContext, you can use write_observations to add new states, then call finish to complete the operation.

Fields

writer: W

The writer to output JSON lines to.

current_state: Value

Current state of the archive (used for diffing).

observation_count: usize

Number of observations already in the archive.

snapshot_interval: Option<usize>

Optional interval for writing snapshots.

finish_strategy: FinishStrategy

How to finish the write operation.

diagnostics: DiagnosticCollector

Diagnostics collected during setup (e.g., warnings from reading existing archive).

Implementations

impl<W: Write> WriteContext<W>

pub fn new( writer: W, current_state: Value, observation_count: usize, snapshot_interval: Option<usize>, finish_strategy: FinishStrategy, ) -> Self

Create a new write context.

pub fn with_diagnostics( writer: W, current_state: Value, observation_count: usize, snapshot_interval: Option<usize>, finish_strategy: FinishStrategy, diagnostics: DiagnosticCollector, ) -> Self

Create a write context with existing diagnostics.

pub fn write_observations<P: AsRef<Path>>( &mut self, files: &[P], ) -> Result<usize, Vec<Diagnostic>>

Write observations for a list of JSON files.

For each file:

1. Reads and parses the JSON
2. Diffs against current state
3. Writes observation events
4. Optionally writes a snapshot if interval is reached
5. Updates current state

Returns the number of observations written.

pub fn finish(self) -> Result<DiagnosticCollector, Vec<Diagnostic>>

Finish the write operation.

This flushes the writer and, for compressed append operations, performs the atomic file replacement.