feat: probe Ollama model digest, emit as model_digest output (v0.3.1)

Closes Compliance Gap 1 from fai/platform :: docs/advanced/
compliance-gaps.md. The module now probes the LLM endpoint's
/api/show on every successful chat invocation and surfaces
the model's SHA-256 digest as a separate output field.

The probe is strictly best-effort:

  - derive_show_url returns None unless the configured endpoint
    ends in /api/chat, so non-Ollama deployments (OpenAI,
    Anthropic) skip the probe entirely.
  - probe_model_digest swallows every failure path (network
    error, non-200 status, malformed JSON, missing digest field)
    and yields None. The plan generation succeeds either way.
  - extract_show_digest looks for digest at top level, then
    details.digest, then model_info.digest — the fields shift
    across Ollama versions, so the lookup is tolerant.

A new generate_plan_with_identity returns a PlanWithIdentity
struct ({plan_json, model_digest}). The original generate_plan
remains as a #[allow(dead_code)] convenience wrapper that
returns just the plan JSON.

The invoke entry point in lib.rs now emits four outputs:
  plan          (json)   — unchanged
  model_endpoint (text)  — unchanged
  model_name    (text)   — unchanged
  model_digest  (text)   — NEW; empty for non-Ollama or stub paths

module.yaml documents the new output and bumps the orchestrator
capability version to 0.3.0 (additive minor; downstream flows
that referenced @^0 keep working).

Eight new tests in src/llm.rs cover the new code paths:
  - URL transform (/api/chat → /api/show)
  - URL transform skipped for non-Ollama endpoints
  - Digest extraction at all three documented JSON locations
  - Digest extraction graceful failure (missing, empty, bad JSON)
  - End-to-end probe success
  - End-to-end probe skipped for non-Ollama
  - End-to-end probe failure swallowed without breaking plan

Total tests: 26 (was 18). Wasm artifact builds with v1.0
imports baked in. Platform-side integration tests in
fai/platform :: orchestrator_llm_path.rs pass against the
new module unchanged.

Bumps the module to 0.3.1 (patch — output schema additively
extended, behaviour unchanged for existing flows).

Signed-off-by: flemming-it <sf@flemming.it>

src/lib.rs

@@ -45,8 +45,8 @@ pub fn invoke(_ctx: Context, inputs: Inputs) -> Result<Outputs, ModuleError> {
         .and_then(payload_text)
         .unwrap_or_default();
 
-    let plan_json = if llm_endpoint.is_empty() {
-        build_stub_plan(goal)
+    let (plan_json, model_digest) = if llm_endpoint.is_empty() {
+        (build_stub_plan(goal), None)
     } else {
         let client = make_client();
         let params = crate::llm::OllamaParams {
@@ -57,14 +57,16 @@ pub fn invoke(_ctx: Context, inputs: Inputs) -> Result<Outputs, ModuleError> {
             available_capabilities: &available_capabilities,
             store_capabilities: &store_capabilities,
         };
-        crate::llm::generate_plan(&client, &params)
-            .map_err(|e| ModuleError::internal(e.to_string()))?
+        let result = crate::llm::generate_plan_with_identity(&client, &params)
+            .map_err(|e| ModuleError::internal(e.to_string()))?;
+        (result.plan_json, result.model_digest)
     };
 
     Ok(Outputs::new()
         .with_json_str("plan", plan_json)
         .with_text("model_endpoint", llm_endpoint)
-        .with_text("model_name", llm_model))
+        .with_text("model_name", llm_model)
+        .with_text("model_digest", model_digest.unwrap_or_default()))
 }
 
 fn payload_text(p: &Payload) -> Option<String> {

src/llm.rs

@@ -127,12 +127,43 @@ pub fn extract_ollama_content(body: &str) -> Result<String, LlmError> {
         .ok_or_else(|| LlmError::Decode("missing message.content".into()))
 }
 
+/// Plan plus model identity captured at invocation time, for
+/// audit logging.
+#[derive(Debug, Clone)]
+pub struct PlanWithIdentity {
+    /// The plan JSON the LLM produced.
+    pub plan_json: String,
+    /// SHA-256 digest of the served model, when reachable. `None`
+    /// for non-Ollama endpoints (OpenAI / Anthropic do not expose
+    /// a per-model digest API) or when the `/api/show` probe failed
+    /// for any reason. The audit trail records this verbatim;
+    /// `None` becomes an empty string in the module output.
+    pub model_digest: Option<String>,
+}
+
 /// Generate a plan via the configured LLM endpoint. Returns the
 /// validated plan JSON ready to be emitted as the module output.
+///
+/// Convenience wrapper kept for callers that do not care about
+/// the model digest. New code should call `generate_plan_with_identity`.
+#[allow(dead_code)]
 pub fn generate_plan<C: LlmClient>(
     client: &C,
     p: &OllamaParams,
 ) -> Result<String, OrchestratorError> {
+    generate_plan_with_identity(client, p).map(|r| r.plan_json)
+}
+
+/// Generate a plan AND probe the LLM endpoint for the model's
+/// SHA-256 digest. The digest probe is best-effort: failures do
+/// not propagate, the digest is simply absent from the result.
+/// This gives compliance-grade audit on Ollama deployments while
+/// staying compatible with cloud providers that do not expose
+/// digests.
+pub fn generate_plan_with_identity<C: LlmClient>(
+    client: &C,
+    p: &OllamaParams,
+) -> Result<PlanWithIdentity, OrchestratorError> {
     if p.endpoint.is_empty() {
         return Err(OrchestratorError::MissingEndpoint);
     }
@@ -146,7 +177,59 @@ pub fn generate_plan<C: LlmClient>(
         .map_err(OrchestratorError::Llm)?;
     let plan_json = extract_ollama_content(&response_body).map_err(OrchestratorError::Llm)?;
     crate::plan::parse_and_validate(&plan_json).map_err(OrchestratorError::Plan)?;
-    Ok(plan_json)
+
+    let model_digest = probe_model_digest(client, p);
+    Ok(PlanWithIdentity {
+        plan_json,
+        model_digest,
+    })
+}
+
+/// Best-effort probe of Ollama's `/api/show` for the model digest.
+/// Any failure (non-Ollama endpoint, network error, parse failure)
+/// returns `None` — never propagates as an error to the caller.
+fn probe_model_digest<C: LlmClient>(client: &C, p: &OllamaParams) -> Option<String> {
+    let show_url = derive_show_url(p.endpoint)?;
+    let body = serde_json::to_string(&serde_json::json!({ "name": p.model })).ok()?;
+    let response = client.post_json(&show_url, &body, p.api_key).ok()?;
+    extract_show_digest(&response)
+}
+
+/// Convert an Ollama `/api/chat` URL into the matching
+/// `/api/show` URL by suffix substitution. Returns `None` if the
+/// endpoint does not end in `/api/chat` — that is the signal that
+/// the endpoint is not Ollama-shaped, so a probe makes no sense.
+pub fn derive_show_url(chat_endpoint: &str) -> Option<String> {
+    if chat_endpoint.ends_with("/api/chat") {
+        let head_len = chat_endpoint.len() - "/api/chat".len();
+        let mut url = String::with_capacity(head_len + "/api/show".len());
+        url.push_str(&chat_endpoint[..head_len]);
+        url.push_str("/api/show");
+        Some(url)
+    } else {
+        None
+    }
+}
+
+/// Extract the SHA-256 digest from a `/api/show` response body.
+/// Looks for the field at top level, then under `details.digest`,
+/// then under `model_info.digest`. Returns `None` if no candidate
+/// resolves to a non-empty string.
+pub fn extract_show_digest(body: &str) -> Option<String> {
+    let v: serde_json::Value = serde_json::from_str(body).ok()?;
+    let candidates = [
+        v.get("digest"),
+        v.get("details").and_then(|d| d.get("digest")),
+        v.get("model_info").and_then(|d| d.get("digest")),
+    ];
+    for cand in candidates {
+        if let Some(s) = cand.and_then(|v| v.as_str()) {
+            if !s.is_empty() {
+                return Some(s.to_string());
+            }
+        }
+    }
+    None
 }
 
 #[derive(Debug, thiserror::Error)]
@@ -351,4 +434,123 @@ mod tests {
             Err(OrchestratorError::Llm(LlmError::MissingInput("llm_model")))
         ));
     }
+
+    // === Compliance Gap 1: model digest probe ===
+
+    #[test]
+    fn derive_show_url_swaps_chat_suffix() {
+        assert_eq!(
+            derive_show_url("http://localhost:11434/api/chat").as_deref(),
+            Some("http://localhost:11434/api/show")
+        );
+        assert_eq!(
+            derive_show_url("https://example.com/v1/api/chat").as_deref(),
+            Some("https://example.com/v1/api/show")
+        );
+    }
+
+    #[test]
+    fn derive_show_url_returns_none_for_non_ollama_endpoints() {
+        assert!(derive_show_url("https://api.openai.com/v1/chat/completions").is_none());
+        assert!(derive_show_url("https://api.anthropic.com/v1/messages").is_none());
+        assert!(derive_show_url("http://localhost:11434/api/chats").is_none());
+        assert!(derive_show_url("/api/chat-something").is_none());
+    }
+
+    #[test]
+    fn extract_show_digest_finds_top_level_field() {
+        let body = r#"{"digest":"sha256:abcdef","details":{"format":"gguf"}}"#;
+        assert_eq!(extract_show_digest(body).as_deref(), Some("sha256:abcdef"));
+    }
+
+    #[test]
+    fn extract_show_digest_falls_back_to_nested_locations() {
+        let nested_details = r#"{"details":{"digest":"sha256:nested-details"}}"#;
+        assert_eq!(
+            extract_show_digest(nested_details).as_deref(),
+            Some("sha256:nested-details")
+        );
+        let nested_info = r#"{"model_info":{"digest":"sha256:nested-info"}}"#;
+        assert_eq!(
+            extract_show_digest(nested_info).as_deref(),
+            Some("sha256:nested-info")
+        );
+    }
+
+    #[test]
+    fn extract_show_digest_returns_none_when_absent_or_empty() {
+        assert!(extract_show_digest(r#"{"modelfile":"..."}"#).is_none());
+        assert!(extract_show_digest(r#"{"digest":""}"#).is_none());
+        assert!(extract_show_digest("not even json").is_none());
+    }
+
+    #[test]
+    fn generate_plan_with_identity_records_digest_when_show_responds() {
+        let canned_plan =
+            r#"{"schema_version":1,"goal":"x","steps":[{"kind":"explain","text":"ok"}]}"#;
+        let canned_chat = format!(
+            r#"{{"message":{{"content":{}}},"done":true}}"#,
+            serde_json::to_string(canned_plan).unwrap(),
+        );
+        let canned_show = r#"{"digest":"sha256:deadbeef"}"#.to_string();
+        // Mock pops from the end — so push show first, chat second.
+        let client = MockClient::new(vec![Ok(canned_show), Ok(canned_chat)]);
+        let p = OllamaParams {
+            endpoint: "http://localhost:11434/api/chat",
+            model: "qwen",
+            api_key: "",
+            goal: "x",
+            available_capabilities: "",
+            store_capabilities: "",
+        };
+        let result = generate_plan_with_identity(&client, &p).unwrap();
+        assert_eq!(result.model_digest.as_deref(), Some("sha256:deadbeef"));
+        assert!(!result.plan_json.is_empty());
+    }
+
+    #[test]
+    fn generate_plan_with_identity_returns_none_digest_for_non_ollama_endpoint() {
+        // Endpoint does not end in /api/chat: probe is skipped
+        // entirely. Only one mock response is consumed.
+        let canned_plan =
+            r#"{"schema_version":1,"goal":"x","steps":[{"kind":"explain","text":"ok"}]}"#;
+        let canned_chat = format!(
+            r#"{{"message":{{"content":{}}}}}"#,
+            serde_json::to_string(canned_plan).unwrap(),
+        );
+        let client = MockClient::new(vec![Ok(canned_chat)]);
+        let p = OllamaParams {
+            endpoint: "https://api.openai.com/v1/chat/completions",
+            model: "gpt",
+            api_key: "k",
+            goal: "x",
+            available_capabilities: "",
+            store_capabilities: "",
+        };
+        let result = generate_plan_with_identity(&client, &p).unwrap();
+        assert_eq!(result.model_digest, None);
+    }
+
+    #[test]
+    fn generate_plan_with_identity_swallows_show_failures() {
+        // The /api/show probe fails (e.g. 500). The plan still
+        // succeeds with `model_digest = None`.
+        let canned_plan =
+            r#"{"schema_version":1,"goal":"x","steps":[{"kind":"explain","text":"ok"}]}"#;
+        let canned_chat = format!(
+            r#"{{"message":{{"content":{}}}}}"#,
+            serde_json::to_string(canned_plan).unwrap(),
+        );
+        let client = MockClient::new(vec![Err(LlmError::Status(500)), Ok(canned_chat)]);
+        let p = OllamaParams {
+            endpoint: "http://localhost:11434/api/chat",
+            model: "qwen",
+            api_key: "",
+            goal: "x",
+            available_capabilities: "",
+            store_capabilities: "",
+        };
+        let result = generate_plan_with_identity(&client, &p).unwrap();
+        assert_eq!(result.model_digest, None);
+    }
 }