| 1 | package openai |
| 2 | |
| 3 | import "strings" |
| 4 | |
| 5 | const ( |
| 6 | thinkOpen = "<think>" |
| 7 | thinkClose = "</think>" |
| 8 | ) |
| 9 | |
| 10 | type thinkState int |
| 11 | |
| 12 | const ( |
| 13 | thinkProbe thinkState = iota |
| 14 | thinkInside |
| 15 | thinkPassthrough |
| 16 | ) |
| 17 | |
| 18 | // thinkSplitter peels a leading <think>...</think> block out of the content |
| 19 | // stream into reasoning text. MiniMax-M3 inlines its chain-of-thought this way |
| 20 | // instead of populating reasoning_content. It only arms on a <think> at the very |
| 21 | // start of the turn, so an answer that merely mentions the tag is never hijacked. |
| 22 | type thinkSplitter struct { |
| 23 | state thinkState |
| 24 | buf string |
| 25 | } |
| 26 | |
| 27 | func (t *thinkSplitter) push(s string) (reasoning, text string) { |
| 28 | switch t.state { |
| 29 | case thinkPassthrough: |
| 30 | return "", s |
| 31 | case thinkInside: |
| 32 | return t.scanClose(s) |
| 33 | } |
| 34 | |
| 35 | t.buf += s |
| 36 | trimmed := strings.TrimLeft(t.buf, " \t\r\n") |
| 37 | if len(trimmed) < len(thinkOpen) { |
| 38 | if strings.HasPrefix(thinkOpen, trimmed) { |
| 39 | return "", "" // still could become <think> once more arrives |
| 40 | } |
| 41 | return "", t.drainPassthrough() |
| 42 | } |
| 43 | if strings.HasPrefix(trimmed, thinkOpen) { |
| 44 | t.state = thinkInside |
| 45 | t.buf = "" |
| 46 | return t.scanClose(trimmed[len(thinkOpen):]) |
| 47 | } |
| 48 | return "", t.drainPassthrough() |
| 49 | } |
| 50 | |
| 51 | func (t *thinkSplitter) scanClose(s string) (reasoning, text string) { |
| 52 | t.buf += s |
| 53 | if idx := strings.Index(t.buf, thinkClose); idx >= 0 { |
| 54 | r := t.buf[:idx] |
| 55 | rest := strings.TrimLeft(t.buf[idx+len(thinkClose):], " \t\r\n") |
| 56 | t.buf = "" |
| 57 | t.state = thinkPassthrough |
| 58 | return r, rest |
| 59 | } |
| 60 | keep := markerSuffixLen(t.buf, thinkClose) |
| 61 | r := t.buf[:len(t.buf)-keep] |
| 62 | t.buf = t.buf[len(t.buf)-keep:] |
| 63 | return r, "" |
| 64 | } |
| 65 | |
| 66 | // flush emits whatever is buffered when the stream ends mid-decision: an |
| 67 | // unterminated <think> block is reasoning; anything else is text. |
| 68 | func (t *thinkSplitter) flush() (reasoning, text string) { |
| 69 | if t.buf == "" { |
| 70 | return "", "" |
| 71 | } |
| 72 | out := t.buf |
| 73 | t.buf = "" |
| 74 | if t.state == thinkInside { |
| 75 | return out, "" |
| 76 | } |
| 77 | return "", out |
| 78 | } |
| 79 | |
| 80 | func (t *thinkSplitter) drainPassthrough() string { |
| 81 | t.state = thinkPassthrough |
| 82 | out := t.buf |
| 83 | t.buf = "" |
| 84 | return out |
| 85 | } |
| 86 | |
| 87 | // markerSuffixLen returns the length of the longest proper suffix of s that is a |
| 88 | // prefix of marker — the tail to hold back in case the rest of the tag arrives |
| 89 | // in the next delta. |
| 90 | func markerSuffixLen(s, marker string) int { |
| 91 | max := len(marker) - 1 |
| 92 | if max > len(s) { |
| 93 | max = len(s) |
| 94 | } |
| 95 | for n := max; n > 0; n-- { |
| 96 | if strings.HasPrefix(marker, s[len(s)-n:]) { |
| 97 | return n |
| 98 | } |
| 99 | } |
| 100 | return 0 |
| 101 | } |
| 102 |