From d4e5b474706b0557616087a47b133240c6cbe1c6 Mon Sep 17 00:00:00 2001
From: Pujitha Paladugu <10557236+pujitha24@users.noreply.github.com>
Date: Sun, 25 Oct 2026 04:06:53 -0700
Subject: [PATCH] Client: Coerce literal `data-herb-set` on seeded states to
 the held type

Motivation: a state declared with an expression default (kind `seeded`)
received a String from a literal `data-herb-set` (e.g. `page=1`), while
`data-herb-increment` wrote a Number. `coerceState` only converts for
boolean, integer and nil, so seeded kinds fell through to the raw text.
The state's type then depended on which action wrote it last, and the
`Herb-State` header could carry `"page":"1"` after `"page":2`.

Approach: in `assignedValue`, when the declared kind is `seeded`, read the
state's current value and coerce the literal to its type: a number for an
integer-looking literal when the state holds a number, a boolean for
`true`/`false` when it holds a boolean. Otherwise (string, null) the raw
text is kept as before.

Limitation: if the seeded state currently holds null, there is no type to
follow and the literal is still written as a String. The `$value` path is
unchanged.

Validation: in javascript/packages/client, `npx vitest run
test/actions.test.ts` passes (44 tests). The new test fails without the
src change and passes with it. Full `npx vitest run`: 772 tests pass; one
test file fails to collect because the generated `state-kinds` module is
missing in this checkout, unrelated to this change (`tsc` reports the same
missing module).

Report: https://github.com/marcoroth/herb/issues/2743
Signed-off-by: Pujitha Paladugu <10557236+pujitha24@users.noreply.github.com>
Assisted-by: claude-sonnet-5-5 (via Claude Code)
---
 .../packages/client/src/actions/actions.ts     | 18 ++++++++++++++++++
 .../packages/client/test/actions.test.ts       | 14 ++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/javascript/packages/client/src/actions/actions.ts b/javascript/packages/client/src/actions/actions.ts
index 8159e8ed8..19f236e42 100644
--- a/javascript/packages/client/src/actions/actions.ts
+++ b/javascript/packages/client/src/actions/actions.ts
@@ -466,9 +466,27 @@ export class Actions implements ElementObserverDelegate, InstructionsDelegate {
       return null
     }
 
+    if (kind === "seeded") {
+      return { value: this.seededLiteral(name, scope, raw) }
+    }
+
     return { value: coerceState(raw, kind) }
   }
 
+  private seededLiteral(name: string, scope: StateScope, raw: string): StateValue {
+    const current = this.state.getState(name, { scope })
+
+    if (typeof current === "number" && /^-?\d+$/.test(raw)) {
+      return Number(raw)
+    }
+
+    if (typeof current === "boolean" && (raw === "true" || raw === "false")) {
+      return raw === "true"
+    }
+
+    return raw
+  }
+
   private toggle(element: Element, rest: string): void {
     const groups: StateGroups = new Map()
 
diff --git a/javascript/packages/client/test/actions.test.ts b/javascript/packages/client/test/actions.test.ts
index 7d9ed0e00..9bf2ca239 100644
--- a/javascript/packages/client/test/actions.test.ts
+++ b/javascript/packages/client/test/actions.test.ts
@@ -28,6 +28,7 @@ const PAGE =
   `<input id="typer" data-herb-set="sort=$value">` +
   `<input id="bound" value="name" data-herb-slot="5:attribute:value">` +
   `<button id="setter" data-herb-set="sort=date">Date</button>` +
+  `<button id="page-reset" data-herb-set="page=1">First</button>` +
   `<select id="chooser" data-herb-set="sort=$value"><option value="date">date</option></select>` +
   `<div id="menu" data-herb-set="mouseenter->open=true mouseleave->open=false">hover</div>` +
   `<div><!--herb-slot:0:conditional--><!--herb-branch:0:1-->closed<!--/herb-slot:0--></div>` +
@@ -55,6 +56,7 @@ const PAGE =
           { name: "failed", kind: "boolean", default: "false", scope: "region" },
           { name: "attempts", kind: "integer", default: "0", scope: "region" },
           { name: "sort", kind: "string", default: '"name"', scope: "region" },
+          { name: "page", kind: "seeded", default: "params.fetch(:page, 1).to_i", scope: "region" },
           { name: "starred", kind: "boolean", default: "false", scope: 2 },
         ],
         reads: { attempts: [1], sort: [5] },
@@ -102,6 +104,18 @@ describe("declarative actions", () => {
     expect(state.getState("open")).toBe(false)
   })
 
+  test("a literal assigned to a seeded state takes the type of the value it holds", () => {
+    state.setState({ page: 3 })
+    click("#page-reset")
+
+    expect(state.getState("page")).toBe(1)
+
+    state.setState({ page: "three" })
+    click("#page-reset")
+
+    expect(state.getState("page")).toBe("1")
+  })
+
   test("two clauses on one attribute both write", () => {
     const order: string[] = []
     const handler = (event: Event): void => {