feat(anthropic): Add support for streaming thinking events

[apappascs]

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feat(anthropic): Add support for streaming thinking events

Add necessary types and update stream processing to handle Anthropic's 'thinking' content blocks and deltas in streaming responses. This resolves an issue where an IllegalArgumentException was thrown for unhandled thinking event types.

example curl request and response:

curl https://api.anthropic.com/v1/messages \
  --header "x-api-key: $ANTHROPIC_API_KEY" \
  --header "anthropic-version: 2023-06-01" \
  --header "content-type: application/json" \
  --data '{
    "model": "claude-3-7-sonnet-20250219",
    "max_tokens": 2048,
    "temperature": 1.0,
    "stream": true,
    "thinking": {
      "type": "enabled",
      "budget_tokens": 1024
    },
    "messages": [
      {
        "role": "user",
        "content": "Are there an infinite number of prime numbers such that n mod 4 == 3?"
      }
    ]
  }'

response

event: message_start
data: {"type":"message_start","message":{"id":"msg_01GhrQGpNXmdBoye6Tsi1zFg","type":"message","role":"assistant","model":"claude-3-7-sonnet-20250219","content":[],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":54,"cache_creation_input_tokens":0,"cache_read_input_tokens":0,"output_tokens":2}}             }

event: content_block_start
data: {"type":"content_block_start","index":0,"content_block":{"type":"thinking","thinking":"","signature":""}    }

event: ping
data: {"type": "ping"}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":"This"}               }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" question is asking about prime numbers $p$ that satisfy"}             }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" $p \\equiv 3 \\p"}   }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":"mod{4}$, i.e., when"} }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" divided by 4, they leave a remainder of "}            }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":"3.\n\nLet's think about whether"}       }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" there are infinitely many such primes.\n\nThe"}         }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" standard proof for the infinitude of pr"}           }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":"imes in general (Euclid's proof"}      }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":") can be adapted to show that"}       }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" there are infinitely many primes in"}             }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" certain residue classes.\n\nFor"} }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" primes $p \\equiv 3 \\pmod{"}     }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":"4}$, we can use"}     }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" Dirichlet's theorem on arithmetic progressions,"}          }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" which states that if $a$ and $m"}       }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":"$ are coprime positive integers, then there are"}      }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" infinitely many primes in the arithmetic progression $a"}      }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":", a+m, a+2m,"}    }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" \\ldots, a+km, \\ldots$"}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":"\n\nIn our case, $a = 3$"}    }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" and $m = 4$, an"}          }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":"d they are coprime since $\\gcd(3"}            }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":", 4) = 1$. So"}   }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" by Dirichlet's theorem, there are"}             }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" infinitely many primes of the form $4"}            }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":"k + 3$ where $k$"}   }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" is a non-negative integer.\n\nSo"}      }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" the answer is yes, there are infinitely many prime"}         }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" numbers $p$ such that $p \\equiv"}           }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"thinking_delta","thinking":" 3 \\pmod{4}$."}  }

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"signature_delta","signature":"ErUBCkYIXXXCIkCptEPsc+PlFas6Gdq/+B/3rtWjwzgKqxXXXWqymf/yvPp8ReVDCJMyV2wIDrXNU1jdozV8yHZ+qMa3O44E8Y8/EgxYLk6hOrtV1cAmxGkaDNjDr6m/yOLkOwvZYSIwMcNcgRez6QxUieKXk7xd5RpQTek7Z5esIkrNg3wgoNRrFJOLyU/adNjF4DJknXXXKh1qC8nCUmxzm7beBoqLq0HtAEsIqQGHxO4LN0S8yRgC"}          }

event: content_block_stop
data: {"type":"content_block_stop","index":0           }

event: content_block_start
data: {"type":"content_block_start","index":1,"content_block":{"type":"text","text":""}               }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":"# Yes, There Are Infinitely Many"}         }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" Primes Where p ≡ "}    }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":"3 (mod 4)\n\nYes"}    }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":", there are infinitely many prime numbers p"}              }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" such that p mod 4 = "}}

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":"3 (or written mathematically as"}           }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" p ≡ 3 (mo"}      }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":"d 4)).\n\nThis can be proven using an"}         }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" adaptation of Euclid's classic"}  }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" proof for the infinitude of primes"}        }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":", though the complete proof is more"}               }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" complex and involves tools from number theory."}               }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":"\n\n## Proof Sketch\n\n1."}         }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" Dirichlet's theorem on primes in arithmetic progressions"}           }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" guarantees that for any coprime integers a and m, there are"}   }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" infinitely many primes in the form"}   }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" a + mk.\n\n2. Since"}       }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" gcd(3,4) = 1"}   }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":", we can apply Dirichlet's theorem"}         }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" with a = 3 and m = "}      }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":"4.\n\n3. Therefore, there are infin"}            }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":"itely many primes of the form 4"} }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":"k + 3.\n\nThe primes p"}               }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" ≡ 3 (mod "}            }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":"4) include 3, 7, 11, 19"}    }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":", 23, 31, 43,"}      }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" 47, 59, 67, "}    }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":"71, ... and they continue indefinitely.\n\nThis"}    }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" result is a special case of the more general fact"}     }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" that prime numbers are equally distributed among the eligible"}              }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" residue classes modulo m ("}}

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":"where \"eligible\" means the residue classes"}      }

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"text_delta","text":" that are coprime to m)."}   }

event: content_block_stop
data: {"type":"content_block_stop","index":1             }

event: message_delta
data: {"type":"message_delta","delta":{"stop_reason":"end_turn","stop_sequence":null},"usage":{"output_tokens":621}           }

event: message_stop
data: {"type":"message_stop"         }

resolves https://github.com/spring-projects/spring-ai/issues/2793