fix(cli): pack runnable ranking requires a pack block or the tsdown default entry

A Vite config without a pack block does not make bare vp pack succeed, so
it no longer counts as pack-runnable; document the per-command runnable
rules normatively in the RFC and docs.

Author: fengmk2

docs/guide/monorepo.md

@@ -197,7 +197,7 @@ error: `vp build` at the workspace root needs a target package.
   Or run every package's build script:  vp run -r build
 ```
 
-Packages that look runnable for the command (an `index.html` or `vite.config.*` for `dev` / `build` / `preview`, a library entry for `pack`) are ranked first in both the picker and the listing.
+Packages that look runnable for the command are ranked first in both the picker and the listing: a `vite.config.*` or root `index.html` for `dev` / `build` / `preview`, and a `pack` config block or tsdown's default `src/index.ts` entry for `pack`.
 
 ### Targeting a package with `-C`
 

packages/cli/binding/src/cli/app_target.rs

@@ -56,11 +56,18 @@ fn is_bare(args: &[String]) -> bool {
 
 /// Heuristic ranking signal: does `dir` look runnable for `command`?
 /// Used for ordering and single-candidate auto-selection, never for hiding.
+/// The rules are documented in rfcs/cwd-flag.md ("The likely-runnable
+/// heuristic"); keep both in sync.
 fn looks_runnable(dir: &AbsolutePathBuf, command: &str) -> bool {
-    let has_vite_config = vite_static_config::has_config_file(dir);
     match command {
-        "pack" => has_vite_config || dir.as_path().join("src/index.ts").is_file(),
-        _ => has_vite_config || dir.as_path().join("index.html").is_file(),
+        // Bare `vp pack` succeeds when the config declares a `pack` block or
+        // tsdown's default entry exists; a Vite config without `pack` does
+        // not make a package packable.
+        "pack" => {
+            vite_static_config::resolve_static_config(dir).get("pack").is_some()
+                || dir.as_path().join("src/index.ts").is_file()
+        }
+        _ => vite_static_config::has_config_file(dir) || dir.as_path().join("index.html").is_file(),
     }
 }
 

rfcs/cwd-flag.md

@@ -276,11 +276,27 @@ The global binary also resolves the local `vite-plus` install from `<dir>`, matc
 
 ### Picker contents
 
-- One row per workspace package: name plus relative path. Nothing is filtered out; packages that look runnable for the command (`vite.config.*` or `index.html` for `dev`/`build`/`preview`, a pack config or library entry for `pack`) rank first, then by path, so apps surface at the top while everything stays searchable.
+- One row per workspace package: name plus relative path. Nothing is filtered out; likely-runnable packages (rules below) rank first, then by path, so apps surface at the top while everything stays searchable.
 - Fuzzy search over name and path via `vite_select::fuzzy_match`, paging identical to the task picker.
 - A runnable workspace root appears as a `(workspace root)` entry, keeping today's "run at root" behavior one keystroke away.
 - With exactly one likely-runnable package, the picker auto-selects it, printing only the `Selected package:` line and the tip.
 
+### The likely-runnable heuristic
+
+Used only for ranking and single-candidate auto-select, never to hide a package: a misjudged package still appears in the picker and listing, just lower. Judged per package directory from file existence and static config extraction; nothing is executed, and parent directories never count.
+
+| Command                     | A package is likely runnable when                                                                                                                                                                          |
+| --------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `dev` / `build` / `preview` | its directory directly contains one of Vite's config file names (`vite.config.{js,mjs,ts,cjs,mts,cts}`, the exact list Vite probes), **or** an `index.html` at the package root (Vite's default app entry) |
+| `pack`                      | its `vite.config.*` declares a `pack` block (read via static extraction; a Vite config without `pack` does not count), **or** `src/index.ts` exists (tsdown's only default entry)                          |
+
+"Exactly one likely-runnable package" means: after sorting rows runnable-first, the first row is runnable and the second is not. Auto-select additionally requires an interactive terminal.
+
+Accepted trade-offs, tolerable because the signal never hides anything and a wrong auto-select is immediately visible (the `Selected package:` line, with the `Tip:` line showing the explicit `-C` form):
+
+- A library whose `vite.config.*` exists only for Vitest or lint settings ranks as runnable for `dev`/`build`/`preview`. A refinement could demote configs whose only top-level keys are tool blocks, via the same static extraction; deferred until it bites in practice.
+- An app whose `index.html` lives outside the package root (custom Vite `root`) or whose config is inherited from a parent directory is not ranked first, and never auto-selects.
+
 ### `defaultPackage` config
 
 ```ts