Understanding Hot Reload Limits

What it does

When your agent uses it

• Teach Claude exactly which Kotlin and Compose changes hot-reload under Compose HotSwan and which trigger a full incremental rebuild fallback
• The user asks why did this rebuild?
• Why isnt this hot reloading?
• Wants to learn HotSwans boundaries before adopting it

Example prompts

• “why did this rebuild?”
• “why isn”
• “, wants to learn HotSwan”
• “/understanding-hot-reload-limits”

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

1. 1Watch the HotSwan tool window status at the moment of save. A schema change surfaces as a "falling back to incremental build" status. That…
2. 2Read the change diff. Decide: is this a body-only change, or a schema change (signature, constructor, interface, field, new resource id…
3. 3If a refactor must change a signature, batch it. First make the body-only changes that get the screen to a working visual state and…
4. 4For inline functions, drop inline for the duration of iteration. Refactor the function out of inline while iterating, hot-reload as…
5. 5For new resource ids, batch all id additions first, accept one rebuild, then iterate on values. Editing Updated Title (existing id)…

What it can do on your machine

Read from SKILL.md and the folder at commit 61223db. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are kotlin and xml).

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • github.com
  • source.android.com

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Understanding Hot Reload Limits loads about 2.6k tokens when it runs. Until then it costs about 212 tokens; SKILL.md has 885 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~212

When it runs · the whole SKILL.md, loaded when a task matches

~2.6k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from rosuH/EasyWatermark at commit 61223db, republished under its Apache-2.0 licence (© rosuH). 885 words, ~2,640 tokens.

name

understanding-hot-reload-limits

description

Use this skill to teach Claude exactly which Kotlin and Compose changes hot-reload under Compose HotSwan and which trigger a full incremental rebuild fallback. Root cause is Android Runtime (ART) class schema immutability; only method bodies are mutable at runtime, so any change to fields, signatures, constructors, interfaces, inline functions, or new resource ids forces a rebuild. Covers the supported-changes table, the rebuild-forcing list, the diff-then-batch workflow that keeps a hot-reload session inside the fast path, and the inline-function and new-resource-id pitfalls. Trigger when the user asks "why did this rebuild?", "why isn't this hot reloading?", wants to learn HotSwan's boundaries before adopting it, or when reviewing a refactor that risks pushing a hot-reload session into a full rebuild.

license

Apache-2.0. See LICENSE for complete terms.

metadata.author

Jaewoong Eum (skydoves)

metadata.keywords

jetpack-compose, performance, hot-reload, hotswan, art, class-redefinition, iteration, developer-experience

// RIGHT (body-only change, hot-reloads)
@Composable
fun Greeting() {
    Text("Hello, World", color = Color.Blue)
}

// WRONG for the fast path (signature change, forces rebuild)
@Composable
fun Greeting(name: String) {
    Text("Hello, $name")
}
// WRONG because: adding a parameter changes the method signature, which violates ART's class
// schema constraint. To stay inside the fast path, introduce the parameter with a default value
// in one save (still a rebuild; accept it once), then iterate on the body across subsequent saves.

// RIGHT (new composable in the same file, hot-reloads on HotSwan 1.2.0+)
@Composable
fun SecondaryAction() {
    Text("New")
}

// WRONG for the fast path (constructor change)
data class User(val id: Long, val name: String, val age: Int)
// WRONG because: adding `age` extends the constructor. On API 30+ HotSwan supports adding
// data class properties; below API 30 the schema change forces a rebuild. When targeting older
// minSdk, batch property additions and accept a rebuild for each.

// WRONG for the fast path
inline fun <T> Modifier.observer(value: T, body: (T) -> Modifier): Modifier = body(value)
// WRONG because: inline functions are expanded at every call site at compile time. There is no
// discrete unit to swap, so editing the inline body forces a full rebuild of every call site.
// Drop `inline` for the duration of iteration, or accept the rebuild.

// RIGHT for the fast path (non-inline variant during iteration)
fun <T> Modifier.observer(value: T, body: (T) -> Modifier): Modifier = body(value)

<!-- RIGHT: value change on an existing id, hot-reloads -->
<string name="title">Updated Title</string>

<!-- WRONG for the fast path: new id, forces rebuild -->
<string name="brand_new_id">Hello</string>
<!-- WRONG because: adding a new string id grows the generated R class. R class regeneration
     is a schema change that ART cannot redefine in place. -->

// RIGHT (body change inside the existing lambda, hot-reloads)
@Composable
fun Row() {
    Button(onClick = { log("tapped") }) { Text("Tap") }
}

// WRONG for the fast path (adds a second lambda, renumbers inner lambda classes)
@Composable
fun Row() {
    Button(onClick = { log("tapped") }) { Text("Tap") }
    Button(onClick = { log("second") }) { Text("Second") }
}
// WRONG because: a Kotlin function's compiled lambdas are anonymous classes named like
// Row$lambda$1, Row$lambda$2. Adding a lambda renumbers them and changes the class table,
// which is a schema change. The fix is to add the second composable as a separate top-level
// function (which is supported), then call it from Row once the structural change has rebuilt.

© rosuH, Apache-2.0. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in .agents/skills/understanding-hot-reload-limits of rosuH/EasyWatermark.

Open the folder on GitHubat commit 61223db

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in rosuH/EasyWatermark, which our catalogue first saw on October 7, 2026.

• skydoves/compose-performance-skillshot-reload/understanding-hot-reload-limits