fix(api): accept all catalog engines on compression PUT schema (#6792)

Reconstructed onto release/v3.8.47 to drop unrelated main-drift (deps/electron/proxy
files belong to #6620, not this PR). Resolved the release's OmniGlyph engine addition
additively (types.ts/compression.ts kept both 'relevance' and 'omniglyph') and extended
stackedPipelineStepSchema + STACKED_PIPELINE_ENGINE_INTENSITIES with the omniglyph branch
so the ENGINE_CATALOG-parity test passes.

Co-authored-by: Pitchfork-and-Torch <Pitchfork-and-Torch@users.noreply.github.com>
Co-authored-by: diegosouzapw <8016841+diegosouzapw@users.noreply.github.com>

src/shared/validation/compressionConfigSchemas.ts

@@ -141,6 +141,19 @@ export const ultraConfigSchema = z
 
 const noConfigSchema = z.object({}).strict();
 
+// Structural engines (session-dedup / ccr / headroom / relevance / llmlingua) do not
+// expose a fixed intensity enum in ENGINE_CATALOG — accept optional free-form intensity
+// and a loose config bag so GET→PUT round-trips of stackedPipeline succeed (#6747).
+const structuralStepConfigSchema = z.record(z.string(), z.unknown()).optional();
+
+/**
+ * Writable stacked-pipeline step shape for PUT /api/settings/compression and
+ * PUT /api/context/combos/[id]. MUST accept every engine id in ENGINE_CATALOG /
+ * GET /api/compression/engines and every engine the DB normalizer keeps
+ * (src/lib/db/compression.ts STACKED_PIPELINE_ENGINE_IDS). Issue #6747: a 5-engine
+ * discriminator rejected session-dedup/ccr/headroom/relevance/llmlingua on write even
+ * though GET returned them.
+ */
 export const stackedPipelineStepSchema = z.discriminatedUnion("engine", [
   z
     .object({
@@ -159,7 +172,8 @@ export const stackedPipelineStepSchema = z.discriminatedUnion("engine", [
   z
     .object({
       engine: z.literal("aggressive"),
-      intensity: z.literal("standard").optional(),
+      // #6747: previously only "standard"; GET / engines.level may echo "ultra"
+      intensity: z.enum(["standard", "ultra"]).optional(),
       config: aggressiveConfigSchema.optional(),
     })
     .strict(),
@@ -177,6 +191,48 @@ export const stackedPipelineStepSchema = z.discriminatedUnion("engine", [
       config: rtkConfigSchema.optional(),
     })
     .strict(),
+  z
+    .object({
+      engine: z.literal("session-dedup"),
+      intensity: z.string().optional(),
+      config: structuralStepConfigSchema,
+    })
+    .strict(),
+  z
+    .object({
+      engine: z.literal("ccr"),
+      intensity: z.string().optional(),
+      config: structuralStepConfigSchema,
+    })
+    .strict(),
+  z
+    .object({
+      engine: z.literal("headroom"),
+      intensity: z.string().optional(),
+      config: structuralStepConfigSchema,
+    })
+    .strict(),
+  z
+    .object({
+      engine: z.literal("relevance"),
+      intensity: z.string().optional(),
+      config: structuralStepConfigSchema,
+    })
+    .strict(),
+  z
+    .object({
+      engine: z.literal("llmlingua"),
+      intensity: z.string().optional(),
+      config: structuralStepConfigSchema,
+    })
+    .strict(),
+  z
+    .object({
+      engine: z.literal("omniglyph"),
+      intensity: z.string().optional(),
+      config: structuralStepConfigSchema,
+    })
+    .strict(),
 ]);
 
 /**
@@ -185,17 +241,23 @@ export const stackedPipelineStepSchema = z.discriminatedUnion("engine", [
  * dropdowns and `stackedPipelineStepSchema`: every engine/intensity offered here is,
  * by construction, accepted by the API update schema.
  *
- * Do NOT add an engine here that is not a branch of `stackedPipelineStepSchema` — the
- * `PUT /api/context/combos/[id]` route validates against that discriminated union and
- * would reject the payload with HTTP 400 (#4955: the UI previously offered `headroom`,
- * `session-dedup`, `ccr`, `llmlingua`, none of which the union accepts, so selecting
- * one silently failed the save). The parity is guarded by a unit test.
+ * Every ENGINE_CATALOG id must appear here (empty intensity list = no level selector).
+ * Parity with `stackedPipelineStepSchema` is guarded by unit tests (#4955 / #6747).
+ * #4955 fixed a UI/schema drift by shrinking the UI; #6747 expands the schema so the
+ * full catalog (and GET stackedPipeline) can round-trip on PUT.
  */
 export const STACKED_PIPELINE_ENGINE_INTENSITIES: Record<string, readonly string[]> = {
-  rtk: ["minimal", "standard", "aggressive"],
-  caveman: ["lite", "full", "ultra"],
+  // Order matches ENGINE_CATALOG stackPriority for readability
+  "session-dedup": [],
+  ccr: [],
   lite: ["lite"],
-  aggressive: ["standard"],
+  rtk: ["minimal", "standard", "aggressive"],
+  headroom: [],
+  relevance: [],
+  caveman: ["lite", "full", "ultra"],
+  aggressive: ["standard", "ultra"],
+  llmlingua: [],
+  omniglyph: [],
   ultra: ["ultra"],
 };