Fix nested theorem numbering: child counters now inherit correct parent number

[Copilot]

Child-counter frames (e.g. corollary) placed inside a parent frame body (e.g. theorem) received the wrong parent number. The counter step was emitted at the end of the figure body, so any nested child read theorem-counter = n-1 instead of n.

#theorem()[         // Theorem 1
  #corollary()[]    // was: Corollary 0.1 — now: Corollary 1.1 ✓
]
#theorem()[         // Theorem 2
  #corollary()[]    // was: Corollary 1.1 — now: Corollary 2.1 ✓
]

Sequential placement (corollary after theorem) is unaffected.

Changes (core.typ)

• make-frame — emit frame-counter.step() at the start of the figure body (before metadata + render), not the end; nested children now see the incremented parent counter at their document location
• display-number — drop the +1 offset; the step precedes here() so the raw counter value is already correct
• theorion-display-number — use the <theorion-frame-metadata> label location (inside the body, after the step) instead of el.location() (the figure anchor, before the step) to maintain correct numbering in outlines and cross-references

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Is it possible to inherit numbering of nested theorems?</issue_title>
<issue_description>Nested theorems work really well graphically. Is it possible to nest theorems and to keep the numbering inherited from the parent theorem?

#import "@preview/theorion:0.4.0": *
#import cosmos.fancy: *
#show: show-theorion
= This works (Sequential)
#theorem()[
]
  #corollary()[]
#theorem()[
]
  #corollary()[]

= Desired (Nested)
#theorem()[
  #corollary(number: 1.1)[] // Hardcoded
]
#theorem()[
  #corollary(number: 2.1)[] // Hardcoded
]

This question originates from https://forum.typst.app/t/how-to-do-hierarchical-counting-for-sub-frames-using-the-frame-it-package/6455?u=vmartel08</issue_description>

<agent_instructions>能不能让
#import "@preview/theorion:0.4.1": *
#import cosmos.fancy: *
#show: show-theorion
#theorem()[
#corollary()[]
]
#theorem()[
#corollary()[]
]

渲染为下图，目前的嵌套编号会存在问题

</agent_instructions>

Comments on the Issue (you are @copilot in this section)

• Fixes Is it possible to inherit numbering of nested theorems? #24

---

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[Copilot]

Pull request overview

This PR fixes hierarchical theorem numbering when a child frame (e.g., corollary) is placed inside a parent frame’s body (e.g., theorem) by ensuring the parent counter is stepped before nested content is laid out.

Changes:

• Move frame-counter.step() to the start of the frame body so nested children see the incremented parent number at their location.
• Update display-number to remove the previous +1 adjustment (counter is now stepped earlier).
• Update theorion-display-number to compute numbering using the <theorion-frame-metadata> location (after stepping) to keep outlines/refs correct.
• Add a regression test and reference snapshot for nested numbering.

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 2 comments.

File	Description
core.typ	Adjusts counter stepping and numbering-location logic to make nested child counters inherit the correct parent number.
tests/issues/i-nested-numbering/test.typ	Adds a regression test covering nested corollaries within theorems (including multiple nested corollaries).
tests/issues/i-nested-numbering/ref/1.png	Adds the visual reference output for the new regression test.

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[Copilot]

get-loc performs a query(...) each time it’s called. Since the numbering function may call get-loc more than once (especially for user-supplied numbering functions), this can repeat an O(N) query unnecessarily. Consider computing the metadata location once (outside the closure) and making get-loc return that cached location.