AttachContainer exposes a Terminal but hard-disables stdin

[shaaravraghu]

Type
Bug

Severity
High

Modules

• spawn-docker-jdk

Evidence

• spawn-docker-jdk/src/main/java/build/spawn/docker/jdk/command/AttachContainer.java:62-64
• The attach request is created with stdin=false.
• AttachContainer.java:75-91 leaves stdin as TODO and returns NullWriter.get() from getInputWriter().

Why this matters

• The returned type is a Terminal, which strongly suggests interactive attach support.
• In practice the attach session is read-only and cannot send input to the container.

Expected behavior

• Either stdin should be wired through correctly, or the API should not expose a writable terminal contract.

Actual behavior

• Consumers receive a terminal whose input writer is a no-op.
• Docker attach is limited to stdout/stderr streaming even though the abstraction suggests interactivity.

Suggested reproduction

1. Attach to a container running an interactive shell.
2. Write to terminal.getInputWriter().
3. Observe that the container never receives the input.

Suggested fix

• Change the attach request to enable stdin when appropriate.
• Connect a real writer to the Docker attach stream.
• If full interactivity is not supported yet, document that clearly or expose a read-only abstraction instead.

Suggested tests

• Add an integration test that attaches to an interactive container and verifies stdin round-tripping.

Issue body ready to paste
AttachContainer returns a Terminal, but it explicitly sends stdin=false in the Docker request and returns NullWriter from getInputWriter(). That makes interactive attach impossible while still advertising a writable terminal abstraction.`