fix(messaging): reduce composer recomposition and typing jank

[jeremiah-k]

Overview

This reduces message-composer recomposition and per-keystroke work, particularly on active meshes where telemetry changes frequently and inline Markdown is enabled.

The composer previously received full Node objects, so updates to telemetry, position, metrics, last-heard time, or other unrelated fields could invalidate the input subtree even when mention-visible identity data had not changed. The live editor also performed more parsing, matching, and draft-persistence work than necessary during rapid typing.

This keeps stored and transmitted message text unchanged while narrowing reactive inputs and bounding mention matching, live styling, and draft persistence.

Changes

Stable composer inputs

• Project nodes into lightweight mention candidates containing only the ID and display names used by the composer.
• Expose those candidates to MessageInput as a persistent ImmutableMap, giving Compose an explicit stability contract.
• Derive the candidate map with structural equality so telemetry-only node updates can leave the input subtree skippable instead of recreating its output transformation or platform input connection.

Bounded typing work

• Cache normalized mention fields once per candidate and normalize each query once.
• Preserve source iteration order while stopping matching at the suggestion limit.
• Fast-path empty queries and plain text.
• Replace full GFM parsing in the live text field with lightweight detection for asterisk bold/italic, strikethrough, and inline code.
• Intentionally leave underscore emphasis raw while editing; sent message bubbles continue to use the full Markdown renderer.
• Debounce draft persistence to SavedStateHandle by 300 ms, cancel superseded writes, and keep send and explicit clear operations immediate.

Presentation-only mentions and Markdown

• Parse Markdown ranges from the immutable source buffer before applying friendly-name substitutions.
• Remap style boundaries through shorter or longer mention replacements.
• Prevent Markdown delimiters in display names from introducing formatting absent from the stored text.
• Ignore bold, italic, and strikethrough delimiters inside inline-code spans while preserving outer emphasis around nested code.
• Preserve raw mention tokens and Markdown delimiters in stored and transmitted messages.

Review guide

The commits are intended to be reviewed independently and in order:

1. fix(messaging): stabilize composer lifecycle and hot paths
   • stable mention projection;
   • bounded matching and live styling;
   • debounced, cancellation-safe draft persistence.
2. fix(messaging): preserve markdown styling through mentions
   • source-first presentation planning;
   • style-range remapping through mention substitutions;
   • delimiter and inline-code isolation.

Regression coverage

Coverage includes:

• case-insensitive mention matching across IDs and display names;
• deterministic ordering and bounded early termination;
• plain-text and incomplete-Markdown fast paths;
• bold, italic, strikethrough, and inline-code styling;
• bold delimiters not being double-counted as italic;
• Markdown ranges before and after multiple mention replacements;
• friendly names containing Markdown delimiters;
• Markdown delimiters inside code spans;
• emphasis surrounding nested code;
• exact trailing-edge draft-persistence timing;
• rapid edits replacing the pending debounce window;
• clearing a draft cancelling pending persistence.

On-device validation

On-device testing was performed while connected to an active mesh with ongoing telemetry updates.

Normal typing is noticeably more responsive, and the earlier focus, keyboard, selection, mention-suggestion, and live-formatting instability was not reproduced during ordinary input.

Holding backspace can still produce some stutter. That appears to be a narrower sustained-edit performance issue and will be investigated separately rather than expanding this PR beyond its current scope.

Scope

This is limited to the message-composer hot path. It does not change transport, BLE scanning or reconnect behavior, database coordination, node identity, or application lifecycle behavior.

Summary by CodeRabbit

• New Features

  • Improved message mentions with faster, more reliable autocomplete and clearer display names.
  • Mention matching now works case-insensitively across IDs and names.
  • Inline Markdown formatting is preserved when mentions are inserted or replaced.

• Bug Fixes

  • Draft messages now save smoothly after brief editing pauses, reducing unnecessary updates.
  • Clearing a draft immediately prevents pending changes from being restored.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: e786250d-47bf-4f0c-b414-b93413d6d7b6

📥 Commits

Reviewing files that changed from the base of the PR and between 847d4b2 and 830e096.

📒 Files selected for processing (5)

• feature/messaging/build.gradle.kts
• feature/messaging/src/commonMain/kotlin/org/meshtastic/feature/messaging/Message.kt
• feature/messaging/src/commonMain/kotlin/org/meshtastic/feature/messaging/MessageViewModel.kt
• feature/messaging/src/commonTest/kotlin/org/meshtastic/feature/messaging/MessageComposerBehaviorTest.kt
• feature/messaging/src/commonTest/kotlin/org/meshtastic/feature/messaging/MessageViewModelTest.kt

🚧 Files skipped from review as they are similar to previous changes (3)

• feature/messaging/src/commonTest/kotlin/org/meshtastic/feature/messaging/MessageViewModelTest.kt
• feature/messaging/src/commonMain/kotlin/org/meshtastic/feature/messaging/MessageViewModel.kt
• feature/messaging/src/commonMain/kotlin/org/meshtastic/feature/messaging/Message.kt

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📝 Walkthrough

Walkthrough

Messaging mentions now use lightweight candidates with live markdown styling and replacement remapping. Draft persistence is debounced, with pending writes canceled when drafts are cleared. Tests cover composer behavior and draft timing.

Changes

Mention composer pipeline

Layer / File(s)	Summary
Candidate-based autocomplete feature/messaging/build.gradle.kts, feature/messaging/src/commonMain/kotlin/org/meshtastic/feature/messaging/Message.kt, feature/messaging/src/commonTest/.../MessageComposerBehaviorTest.kt	Mention candidates replace full nodes for matching, rendering, and candidate-ID insertion, with preview wiring and matching tests updated.
Mention and markdown transformation feature/messaging/src/commonMain/kotlin/org/meshtastic/feature/messaging/Message.kt, feature/messaging/src/commonTest/.../MessageComposerBehaviorTest.kt	Live inline markdown spans are detected and remapped after friendly-name mention replacements, with coverage for code spans, offsets, and delimiter handling.

Draft persistence

Layer / File(s)	Summary
Debounced draft persistence feature/messaging/src/commonMain/kotlin/org/meshtastic/feature/messaging/MessageViewModel.kt, feature/messaging/src/commonTest/kotlin/org/meshtastic/feature/messaging/MessageViewModelTest.kt	Draft edits update memory immediately and persist after 300 ms; clearing cancels pending persistence and is covered by tests.

Estimated code review effort: 4 (Complex) | ~45 minutes

Sequence Diagram(s)

sequenceDiagram
  participant MessageScreen
  participant MessageInput
  participant MentionCandidateMatcher
  participant MentionOutputPlan
  participant LiveMarkdownParser
  MessageScreen->>MessageInput: provide mention candidates
  MessageInput->>MentionCandidateMatcher: match mention query
  MentionCandidateMatcher-->>MessageInput: return ordered suggestions
  MessageInput->>MentionOutputPlan: replace mention tokens
  MentionOutputPlan->>LiveMarkdownParser: remap markdown spans
  LiveMarkdownParser-->>MessageInput: return styled composer output

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Possibly related PRs

• meshtastic/Meshtastic-Android#6108: Related refactoring of the messaging mention autocomplete and token replacement pipeline.
• meshtastic/Meshtastic-Android#6234: Related inline markdown styling and mention span remapping work.

Suggested labels: refactor, ui

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main goal of the changes: reducing composer recomposition and typing jank in messaging.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 Checkov (3.3.8)

feature/messaging/build.gradle.kts

Traceback (most recent call last):
File "/usr/local/bin/checkov", line 2, in
from checkov.main import Checkov
ModuleNotFoundError: No module named 'checkov'

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[jamesarich]

Went through this in detail — the correctness story is solid: raw text in the buffer is what's stored and transmitted (OutputTransformation is display-only), so the wire format and iOS parity are untouched; the live-styling regexes are index-safe on unterminated/nested/multibyte input; rename propagation works through the derived candidate map; the span remapping math checks out through short/long replacements; and parsing before replacement closes the delimiter-injection hole. The cached normalization and bounded lazy matching do what the description says, with deterministic ordering. Nice work.

Four smaller items, none blocking:

1. The headline recomposition claim is only partially realized. MessageScreen still reads nodes directly, so it recomposes on every telemetry tick — and the candidate map is a plain Map, which is unstable to the Compose compiler, so MessageInput is compared by reference and re-executes anyway (cheap re-execution thanks to the inner memoization, but not the skipping the description implies). Passing a kotlinx.collections.immutable.ImmutableMap (or an @Immutable wrapper) would make the claim fully true for one line of change.

2. Device validation. The Validation section lists unit coverage only — for a jank PR I'd like the usual on-device pass (busy mesh, telemetry churn, inline Markdown on) before merge, even though the risk is low with the wire format untouched.

3. PR body nit: "Removed the ineffective onCleared() draft write" — there's no onCleared at the merge base or on main, and nothing of the sort in this diff. Worth correcting so the changelog doesn't record a phantom change.

4. Cosmetic, worth a KDoc note: the live detectors cover *, **, ~~, and backticks but not underscore emphasis, so _x_/__x__ previews unstyled in the composer while styling correctly in the sent bubble. Fine as a trade — just document it at liveInlineMarkdownStyleRanges so it doesn't come back as a bug report. (Also: MessageComposerPerformanceTest asserts correctness, not performance — a rename would keep expectations honest.)

With #2 done (and ideally #1), this is ready.

[jeremiah-k]

@jamesarich I’ve addressed the earlier review feedback and completed another on-device pass. Normal typing is noticeably improved. There is still some stutter when holding backspace, which I plan to investigate further as part of follow-up lifecycle work, but I don’t think that should block this PR in its current scope.

During final testing I also encountered BLE reconnect and scan-lifecycle failures. Those issues are unrelated to the composer changes and are addressed separately in #6384, so there is no code or merge-order dependency between the two PRs.

[jamesarich]

Appreciate it - thank you!