diff --git a/src/openhuman/agent_registry/agents/orchestrator/prompt.md b/src/openhuman/agent_registry/agents/orchestrator/prompt.md
index d7ae7ea0f1..e896f40ec4 100644
--- a/src/openhuman/agent_registry/agents/orchestrator/prompt.md
+++ b/src/openhuman/agent_registry/agents/orchestrator/prompt.md
@@ -191,6 +191,27 @@ Modes:
 
 Start cheap (`query_source` / `smart_walk` summaries), only drill_down/fetch_leaves when you need verbatim content.
 
+## Presentation generation
+
+`generate_presentation` builds a `.pptx` deck from a structured slide spec via a native Rust engine (`ppt-rs`) running in-process — no Python subprocess, no managed venv. Use it for any "make slides", "build a deck", "draft a presentation", "create a pitch" request.
+
+**Grounding rule (do not skip).** Before calling `generate_presentation` on a topical or factual deck — anything where the slides need real-world facts, current events, statistics, names, dates, quotes, or domain context — you MUST first establish a grounding context. Pick at least one:
+
+- `memory_tree` (`query_source` / `smart_walk`) — when the topic plausibly lives in the user's ingested history (their notes, prior chats, emails on the subject).
+- `research` — when the topic needs live web facts (current events, recent stats, comparative product data, anything time-sensitive).
+- `query_memory` — when the user has previously summarised the exact topic in this thread or in a saved memory.
+
+Only after the grounding tool returns may you call `generate_presentation`, and the slide bullets / body / speaker_notes you pass MUST be drawn from the grounding output — not invented from priors.
+
+**When to skip grounding.** You may dispatch `generate_presentation` directly when:
+
+- The user pasted source material in the same turn (text, doc summary, bullet list to convert).
+- A prior turn in this same thread already established the source material (and you can quote from it).
+- The deck is content-free or structural (e.g. "make me a 3-slide blank template titled 'Q3 Review'", "an empty deck with a title slide and two body slides").
+- The user explicitly waived grounding ("don't research, just generate from your priors", "I know it'll be approximate").
+
+**Why this rule exists.** Without grounding, the model invents slide bullets and speaker notes from training-data priors. That confabulates statistics, misattributes quotes, and ages out fast. A single `research` or `memory_tree` call up front grounds the deck in verifiable sources and lets the slides cite real material instead of fabricated text.
+
 ## Citations
 
 When your answer is informed by retrieved memory, cite it with footnote markers:
diff --git a/src/openhuman/agent_registry/agents/orchestrator/prompt.rs b/src/openhuman/agent_registry/agents/orchestrator/prompt.rs
index 08cf5a2536..3a41bfb2da 100644
--- a/src/openhuman/agent_registry/agents/orchestrator/prompt.rs
+++ b/src/openhuman/agent_registry/agents/orchestrator/prompt.rs
@@ -338,6 +338,74 @@ mod tests {
         assert!(!body.contains("- **linear**"));
     }
 
+    #[test]
+    fn build_requires_grounding_before_generate_presentation() {
+        // #2780 grounding rule: orchestrator must ground a topical/factual
+        // deck via `memory_tree` / `research` / `query_memory` before
+        // dispatching `generate_presentation`. The rule is expressed in
+        // `prompt.md` and must reach the assembled body verbatim — the
+        // test pins both the section header and the load-bearing "do
+        // not skip" instruction so a future prompt refactor can't
+        // quietly drop the guardrail. The live-web grounding option is
+        // named `research` (the researcher agent's `delegate_name`
+        // override, not the default `delegate_researcher` /
+        // `delegate_research`); it must match the actual tool name the
+        // orchestrator exposes so the model can dispatch it instead of
+        // hallucinating a non-tool.
+        let body = build(&ctx_with(&[])).unwrap();
+        assert!(
+            body.contains("## Presentation generation"),
+            "presentation section header missing from orchestrator prompt"
+        );
+        assert!(
+            body.contains("Grounding rule (do not skip)"),
+            "grounding rule missing from presentation section"
+        );
+        assert!(
+            body.contains("Before calling `generate_presentation`"),
+            "grounding pre-condition phrasing missing from presentation section"
+        );
+        // Each of the three permitted grounding tools must be named so
+        // the model knows the menu, not just the constraint.
+        assert!(body.contains("`memory_tree`"));
+        assert!(
+            body.contains("`research`"),
+            "grounding rule must name the researcher tool by its actual \
+             delegate_name (`research`), not `delegate_research`"
+        );
+        assert!(
+            !body.contains("`delegate_research`"),
+            "stale `delegate_research` reference — researcher's \
+             delegate_name override is `research`"
+        );
+        assert!(body.contains("`query_memory`"));
+        // All four waiver escape hatches must reach the assembled body
+        // verbatim — without each one the rule blocks a legitimate
+        // dispatch case. Per graycyrus on #3029: pinning only one waiver
+        // lets a future prompt edit silently drop or expand the list and
+        // the safety-critical guardrail decays unnoticed.
+        // (1) user pasted source material in the same turn.
+        assert!(
+            body.contains("user pasted source material"),
+            "waiver clause for pasted-source decks missing"
+        );
+        // (2) prior turn in same thread already established source material.
+        assert!(
+            body.contains("prior turn in this same thread"),
+            "waiver clause for prior-turn established material missing"
+        );
+        // (3) structural / content-free deck (blank template, layout-only).
+        assert!(
+            body.contains("content-free or structural"),
+            "waiver clause for structural / content-free decks missing"
+        );
+        // (4) explicit user waiver ("don't research, just generate…").
+        assert!(
+            body.contains("explicitly waived grounding"),
+            "waiver clause for explicit user waiver missing"
+        );
+    }
+
     #[test]
     fn build_omits_guide_when_no_integrations_connected() {
         let integrations = vec![ConnectedIntegration {
diff --git a/src/openhuman/tools/impl/presentation/tests.rs b/src/openhuman/tools/impl/presentation/tests.rs
index a8451f9c7b..9e92ba4c19 100644
--- a/src/openhuman/tools/impl/presentation/tests.rs
+++ b/src/openhuman/tools/impl/presentation/tests.rs
@@ -184,3 +184,19 @@ fn truncate_stderr_caps_payload_with_suffix() {
     let short = "tiny stderr";
     assert_eq!(PresentationError::truncate_stderr(short), short);
 }
+
+#[test]
+fn unsupported_file_type_display_includes_extension_and_supported() {
+    // Reserved-for-future variant (#2780): confirms the Display impl
+    // renders both the rejected extension and the supported set so a
+    // downstream mapper can surface a user-correctable message verbatim
+    // once a `format` selector lands.
+    let err = PresentationError::UnsupportedFileType {
+        extension: "key".to_string(),
+        supported: "pptx".to_string(),
+    };
+    let rendered = err.to_string();
+    assert!(rendered.contains("unsupported file type"));
+    assert!(rendered.contains("'key'"));
+    assert!(rendered.contains("supported: pptx"));
+}
diff --git a/src/openhuman/tools/impl/presentation/types.rs b/src/openhuman/tools/impl/presentation/types.rs
index 10845f6c1f..ddc6b84ab3 100644
--- a/src/openhuman/tools/impl/presentation/types.rs
+++ b/src/openhuman/tools/impl/presentation/types.rs
@@ -90,6 +90,19 @@ pub enum PresentationError {
 
     #[error("presentation generation exceeded {timeout_secs}s timeout")]
     GenerationTimeout { timeout_secs: u64 },
+
+    /// Reserved for the planned `format` selector that will let callers
+    /// request alternative deck formats (`.pdf` / `.key` / image
+    /// strips). Today the tool only emits `.pptx`, so this variant is
+    /// not constructed by `execute` — it exists ahead of #2780's
+    /// follow-up wiring so downstream error-handling sites can pattern-
+    /// match exhaustively without a churn-y enum bump later.
+    #[allow(dead_code)]
+    #[error("unsupported file type '{extension}'; supported: {supported}")]
+    UnsupportedFileType {
+        extension: String,
+        supported: String,
+    },
 }
 
 impl PresentationError {
@@ -111,9 +124,9 @@ impl PresentationError {
     }
 }
 
-/// Validate the input early — before spawning Python — so the agent
-/// gets a structured `InvalidInput` it can self-correct on instead of
-/// a generic Python traceback.
+/// Validate the input early — before invoking the `ppt-rs` engine — so
+/// the agent gets a structured `InvalidInput` it can self-correct on
+/// instead of a generic engine error.
 pub(super) fn validate_input(input: &GeneratePresentationInput) -> Result<(), PresentationError> {
     if input.title.trim().is_empty() {
         return Err(PresentationError::InvalidInput {
diff --git a/tests/orchestrator_presentation_wiring.rs b/tests/orchestrator_presentation_wiring.rs
new file mode 100644
index 0000000000..925a453af0
--- /dev/null
+++ b/tests/orchestrator_presentation_wiring.rs
@@ -0,0 +1,58 @@
+//! Pins the orchestrator's `generate_presentation` wiring contract
+//! (#2780 — companion to the tool itself shipped in #2778).
+//!
+//! Two invariants:
+//!
+//! 1. The orchestrator's `agent.toml` MUST list `generate_presentation`
+//!    in `[tools].named`. Without this entry the orchestrator's
+//!    function-calling schema does not include the tool and the
+//!    "create slides" routing case from parent epic #1535 silently
+//!    falls back to refusing the request.
+//!
+//! 2. The `code_executor` agent MUST NOT list `generate_presentation`.
+//!    Presentation rendering is not a code-exec task: it runs in-process
+//!    via the native Rust `ppt-rs` engine (no Python, no subprocess,
+//!    distinct from code_executor's `node_exec` / shell surface), and
+//!    exposing the tool to code_executor would create a second,
+//!    duplicate dispatch path that bypasses the orchestrator's
+//!    grounding-rule prompt.
+//!
+//! Exact-line matching (not substring) so commented-out entries or
+//! prefixed names (`generate_presentation_v2`, `generate_presentation_legacy`)
+//! cannot satisfy the assertion accidentally.
+
+const ORCHESTRATOR_TOML: &str =
+    include_str!("../src/openhuman/agent_registry/agents/orchestrator/agent.toml");
+
+const CODE_EXECUTOR_TOML: &str =
+    include_str!("../src/openhuman/agent_registry/agents/code_executor/agent.toml");
+
+const TOOL_NAME: &str = "generate_presentation";
+
+fn lists_named_tool(toml: &str, name: &str) -> bool {
+    let bare = format!("\"{name}\"");
+    let trailing = format!("\"{name}\",");
+    toml.lines()
+        .map(str::trim)
+        .any(|line| line == bare || line == trailing)
+}
+
+#[test]
+fn orchestrator_lists_generate_presentation() {
+    assert!(
+        lists_named_tool(ORCHESTRATOR_TOML, TOOL_NAME),
+        "orchestrator agent.toml must list '{TOOL_NAME}' as a named tool entry — \
+         removing it silently disables the 'create slides' routing case (#1535)"
+    );
+}
+
+#[test]
+fn code_executor_does_not_list_generate_presentation() {
+    assert!(
+        !lists_named_tool(CODE_EXECUTOR_TOML, TOOL_NAME),
+        "code_executor agent.toml must NOT list '{TOOL_NAME}' — pptx rendering \
+         is not a code-exec task; it runs in-process via the native Rust ppt-rs \
+         engine and adding it here would bypass the orchestrator grounding-rule \
+         prompt (#2780)"
+    );
+}