[codex] Add generic model context window hints

src/harness/mod.rs

@@ -47,7 +47,7 @@ pub use message::{ContentBlock, Message};
 pub use model::{
     CapabilitySet, Modalities, ModelProfile, ModelRequest, ModelResponse, ModelStatus, ModelStream,
     ModelStreamItem, ProviderError, ResponseFormat, StreamAccumulator, ToolChoice,
-    collect_model_stream,
+    collect_model_stream, context_window_for_model_id,
 };
 pub use no_progress::{
     DEFAULT_IDENTICAL_HALT_THRESHOLD, NoProgress, NoProgressTracker, ToolAttempt,

src/harness/model/mod.rs

@@ -27,6 +27,82 @@ use crate::harness::usage::Usage;
 
 pub use types::*;
 
+/// How a context-window pattern is matched against a model id.
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+enum ContextPatternMatch {
+    /// Pattern may appear anywhere in the lowercased model id.
+    Substring,
+    /// Pattern must be a complete segment delimited by common provider/id
+    /// separators. This avoids false positives for short model ids such as
+    /// `o1` and `o3`.
+    Segment,
+}
+
+/// Generic context-window hints for common provider model families.
+///
+/// These are deliberately provider-neutral fallbacks, not a pricing catalog.
+/// Hosts should prefer authoritative provider/catalog metadata when available
+/// and use this only when a raw model id needs a conservative pre-dispatch
+/// budget.
+///
+/// Order matters: lookup returns the first matching entry, so more-specific
+/// substrings such as `gpt-4.1` and `gpt-4-turbo` must stay before broader
+/// patterns such as `gpt-4` that would otherwise shadow them.
+const MODEL_CONTEXT_PATTERNS: &[(&str, ContextPatternMatch, u64)] = &[
+    ("claude-haiku-4.5", ContextPatternMatch::Substring, 200_000),
+    ("claude-haiku-4", ContextPatternMatch::Substring, 200_000),
+    ("claude-haiku", ContextPatternMatch::Substring, 200_000),
+    ("claude-sonnet-4", ContextPatternMatch::Substring, 200_000),
+    ("claude-opus-4", ContextPatternMatch::Substring, 200_000),
+    ("claude-3-5-sonnet", ContextPatternMatch::Substring, 200_000),
+    ("claude-3-5-haiku", ContextPatternMatch::Substring, 200_000),
+    ("claude-3-opus", ContextPatternMatch::Substring, 200_000),
+    ("gpt-4.1", ContextPatternMatch::Substring, 1_047_576),
+    ("gpt-4o", ContextPatternMatch::Substring, 128_000),
+    ("gpt-4-turbo", ContextPatternMatch::Substring, 128_000),
+    ("gpt-4", ContextPatternMatch::Substring, 128_000),
+    ("gpt-3.5", ContextPatternMatch::Substring, 16_385),
+    ("o1", ContextPatternMatch::Segment, 200_000),
+    ("o3", ContextPatternMatch::Segment, 200_000),
+    ("deepseek", ContextPatternMatch::Substring, 128_000),
+    ("gemma3", ContextPatternMatch::Substring, 8_192),
+    ("gemma", ContextPatternMatch::Substring, 8_192),
+    ("llama-3", ContextPatternMatch::Substring, 128_000),
+    ("llama3", ContextPatternMatch::Substring, 128_000),
+];
+
+fn matches_context_pattern(lower: &str, pattern: &str, mode: ContextPatternMatch) -> bool {
+    match mode {
+        ContextPatternMatch::Substring => lower.contains(pattern),
+        ContextPatternMatch::Segment => {
+            let model_name = lower.rsplit(['/', ':']).next().unwrap_or(lower);
+            model_name
+                .split(['-', '_', '.'])
+                .next()
+                .is_some_and(|segment| segment == pattern)
+        }
+    }
+}
+
+/// Returns a generic context-window hint for a raw provider model id.
+///
+/// Returns `None` for unknown ids rather than guessing. Hosts with product tier
+/// aliases, local runtime profiles, or authoritative provider catalogs should
+/// check those first and use this helper as a last generic fallback.
+pub fn context_window_for_model_id(model: &str) -> Option<u64> {
+    let normalized = model.trim();
+    if normalized.is_empty() {
+        return None;
+    }
+
+    let lower = normalized.to_ascii_lowercase();
+    MODEL_CONTEXT_PATTERNS
+        .iter()
+        .find_map(|(pattern, mode, window)| {
+            matches_context_pattern(&lower, pattern, *mode).then_some(*window)
+        })
+}
+
 impl std::fmt::Display for ProviderError {
     /// Renders the same human-readable shape real provider adapters used to
     /// build by hand before flattening it into a plain

src/harness/model/test.rs

@@ -100,6 +100,43 @@ fn lifecycle_helpers_gate_retired_and_deprecated_models() {
     assert!(retired.is_deprecated());
 }
 
+#[test]
+fn context_window_patterns_cover_common_provider_families() {
+    assert_eq!(context_window_for_model_id("gpt-4.1"), Some(1_047_576));
+    assert_eq!(
+        context_window_for_model_id("openai/gpt-4o-mini"),
+        Some(128_000)
+    );
+    assert_eq!(
+        context_window_for_model_id("github_copilot/claude-haiku-4.5"),
+        Some(200_000)
+    );
+    assert_eq!(context_window_for_model_id("deepseek-chat"), Some(128_000));
+    assert_eq!(context_window_for_model_id("gemma3:4b"), Some(8_192));
+    assert_eq!(context_window_for_model_id("llama3:8b"), Some(128_000));
+    assert_eq!(context_window_for_model_id("totally-unknown-model"), None);
+    assert_eq!(context_window_for_model_id("   "), None);
+}
+
+#[test]
+fn o1_o3_context_patterns_require_segment_boundaries() {
+    assert_eq!(context_window_for_model_id("o1"), Some(200_000));
+    assert_eq!(context_window_for_model_id("o1-mini"), Some(200_000));
+    assert_eq!(context_window_for_model_id("o3-mini"), Some(200_000));
+    assert_eq!(
+        context_window_for_model_id("openai/o1-preview"),
+        Some(200_000)
+    );
+
+    assert_eq!(context_window_for_model_id("solo1-7b"), None);
+    assert_eq!(context_window_for_model_id("proto3-chat"), None);
+    assert_eq!(context_window_for_model_id("octo3thing"), None);
+    assert_eq!(
+        context_window_for_model_id("ollama/mistral-for-o1-benchmark"),
+        None
+    );
+}
+
 #[test]
 fn cacheable_prefix_ids_in_order() {
     let req = ModelRequest::new(vec![]).with_cache_segments(vec![