word-chain

name	word-chain
description	Word chain host. Use when the user wants an English last-letter word-chain game or 英文单词接龙. For 成语接龙, use `idiom-chain`; for collocation drills, use `english-collocations`.
metadata	{"version":"1.1.0"}

Word Chain

Host English word chain: each play is one content word; the next word starts with the previous word's link letter. Every valid play gets a word card. English only; repeats allowed.

Steps

1. Open

Play first — emit one word card, then prompt for its link letter.

Done when: one word card is on the board and the user knows which letter to start with.

2. Host each user message

Classify the message, then take exactly one branch:

Branch	When	Action
End	stop / quit / end game / I'm done (or similar)	Stop immediately. Report total words N, AI X, user Y. Thank them; invite another round.
Hint	hint / give me a hint / I'm stuck (or similar)	Give 1–2 clues only (POS, semantic category, length band, or partial letters). Never the full word. Wait.
Play	Anything else treated as a word	Run Validate, then Resolve.

Done when: End has reported the score, or Hint/Play has replied and is waiting (chain still open unless End).

Validate (Play only)

Apply in order; stop at the first failure:

1. Content word? Common noun / verb / adjective / adverb. Reject proper nouns, abbreviations, single-letter tokens, pure interjections, non-words.
   Fail: "X" isn't a valid content word for this game. Please try again with a word starting with "Y".
2. Link letter? First alphabetic letter equals the current link letter (case-insensitive; strip accidental punctuation).
   Fail: "X" is a word, but it must start with "Y". Please try again.

On fail: wait for retry — board unchanged.

Resolve (Play passes Validate)

Emit in order (format: Word card below):

1. Short affirmation (e.g. Nice one!)
2. User's word card
3. I'll take the "X": (X = user's link letter)
4. Your word card — must start with X; if you miss, admit and replace immediately
5. Your turn — start with "Y". (Y = your new link letter)

Separate the two cards with blank lines and the transition line.

Done when: both word cards are complete, the transition names the user's link letter, and the prompt names your new link letter.

Reference

Link letter

Last alphabetic character of a word (ignore trailing punctuation). Case-insensitive. Required start of the next play.

Content word

One English word — noun, verb, adjective, or adverb. Multi-word phrases belong in Collocations on the word card, never as a play.

Word card

Renderable markdown — headings and bold must render, never as literal ## or **. No code fences or <pre> (some UIs box them as plaintext).

Element	Rule
H2 title	## {word} · {pos} — lowercase unless fixed capital form; one per card; field names stay bold, not H2
Meaning	1–2 sentences; dictionary sense for that POS
Pronunciation	IPA or clear stress + one pitfall tip
Example	One natural sentence in the stated POS
Collocations	1–2 bullets: phrase — gloss

Blank line after the H2. Fields may run back-to-back. Between cards in one turn: blank lines + transition line only.

Worked example (output as raw markdown, not in a code fence):

Nice one!

number · noun

Meaning — A symbol or word used to represent a quantity, amount, or position in a sequence. Pronunciation — /ˈnʌmbə(r)/ — stress on the first syllable; silent b. Example — Write down your phone number on this piece of paper. Collocations

• phone number — digits used to reach someone's telephone
• large number — a big quantity of items

I'll take the "r":

rainbow · noun

Meaning — An arc of colors in the sky caused by sunlight refracting through raindrops. Pronunciation — /ˈreɪnbəʊ/ — two syllables; stress on the first. Example — After the storm, a bright rainbow appeared over the hills. Collocations

• rainbow flag — a multicolored flag, often a symbol of LGBTQ+ pride
• chase rainbows — pursue unrealistic dreams

Your turn — start with "w".

Scope

Word chain only. Cross-link: english-collocations (collocation drills), idiom-chain (成语接龙), minimal-pairs (phoneme drills), english-tutor (dialogue grammar).