Add --stream flag to subscribe for mutable message streaming

[zknill]

Upgrade ably SDK from 2.14.0 to 2.18.0 to support mutable messages. Add a --stream flag to channels subscribe that concatenates message.append data for the same serial, streaming tokens in-place on TTY terminals. In JSON mode, action and serial fields are included in the output when --stream is enabled.

Update the publish command's publisher callback signature to accept the new PublishResult return type from the upgraded SDK.

Summary by CodeRabbit

• Dependencies

  • Updated Ably library to version 2.18.0.

• New Features

  • Added --stream flag to channel subscription command enabling inline accumulation and display of messages grouped by serial number.

• Tests

  • Added test coverage for stream mode functionality including message handling, output formatting, and serial tracking behavior.

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Project	Deployment	Actions	Updated (UTC)
cli-web-cli	Building	Preview, Comment	Feb 27, 2026 3:59pm

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Review profile: CHILL

Plan: Pro

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📥 Commits

Reviewing files that changed from the base of the PR and between 040e7df and 122578d.

⛔ Files ignored due to path filters (1)

• pnpm-lock.yaml is excluded by !**/pnpm-lock.yaml

📒 Files selected for processing (4)

• package.json
• src/commands/channels/publish.ts
• src/commands/channels/subscribe.ts
• test/unit/commands/channels/subscribe.test.ts

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Walkthrough

The PR updates the Ably dependency from 2.14.0 to 2.18.0, widens the publisher callback type to optionally return a PublishResult, and introduces a new stream-based output mode to the subscribe command that concatenates inline message data per serial with corresponding test coverage.

Changes

Cohort / File(s)	Summary
Dependency Update package.json	Ably library updated from ^2.14.0 to ^2.18.0.
Publisher Callback Type src/commands/channels/publish.ts	Publisher callback signature widened to accept Promise<void | Ably.PublishResult> instead of Promise<void>, allowing optional result returns.
Stream Mode Feature src/commands/channels/subscribe.ts	Adds --stream flag and stream handling with state fields (streamCurrentSerial, streamAppendCount), new methods (handleStreamMessage, finalizeStream), and modified message routing for inline token streaming and accumulation per serial.
Stream Mode Tests test/unit/commands/channels/subscribe.test.ts	Comprehensive test suite validating stream mode behavior: message.create display, successive message.append accumulation, JSON output inclusion of action/serial, serial reset logic, and non-serial message display.

Sequence Diagram

sequenceDiagram
    participant User as User/CLI
    participant Subscribe as subscribe.ts
    participant Handler as handleStreamMessage
    participant Output as Stdout/TTY

    User->>Subscribe: channels:subscribe --stream
    Subscribe->>Subscribe: Initialize streamCurrentSerial=null, streamAppendCount=0
    
    loop For each received message
        Subscribe->>Handler: Process message via handleStreamMessage
        
        alt Message is create/append action
            Handler->>Handler: Check if serial matches streamCurrentSerial
            alt Serial changed or first message
                Handler->>Output: Finalize previous stream (if any) with count
                Handler->>Handler: Reset streamCurrentSerial, streamAppendCount=0
            end
            Handler->>Handler: Increment streamAppendCount
            Handler->>Output: Stream/delta output in-place (TTY mode)
        else Other action types
            Handler->>Output: Display message with standard structured log
        end
    end
    
    Subscribe->>Handler: finalizeStream() at loop end
    Handler->>Output: Emit final count summary

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Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Poem

🐰 A streaming burrow of data flows free,
Serials aligned, appends agree,
Messages nest in their proper place,
TTY rewrite—a swift update's grace.
Ably hops forward, version anew—
Dependencies dance, tests debut!

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'Add --stream flag to subscribe for mutable message streaming' accurately and concisely describes the main change: adding a streaming feature to the subscribe command with support for mutable messages.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

• 📝 Generate docstrings (stacked PR)
• 📝 Generate docstrings (commit on current branch)

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch zak/mutable-messages-streaming

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