MCP: authored synonym produces duplicate autocomplete suggestions and snippets #69

Observed released behaviour

The published Rust MCP 1.21.22-rc.1 returns duplicate suggestions for one authored synonym. This reproduces both through the official Python MCP SDK and through the actual released Kilo 7.8.8 backend. It is distinct from the fixed unknown-role defect #63 and synonym-retrieval defect #62.

Tested macOS ARM64 executable SHA-256: 48da284f633ddd34c70e7f028abadd40c99d67d4dff5e518ed1dc966802ecfd7.

Portable fixture

Create concepts/Risk.md:

# Risk
synonyms:: Concern

Use three separate read-only corpus Markdown documents:

Risk: supplier delays could affect the launch date.
Risk decision: approve a second supplier as the mitigation.
Risk action: review lead times every Friday.

Configure a selected/default role named project in .terraphim/config.json, using relevance_function: "terraphim-graph", kg.knowledge_graph_local.input_type: "markdown", an absolute kg.knowledge_graph_local.path to the concepts directory, and one Ripgrep haystack pointing at the separate corpus directory. Set public/publish false, terraphim_it false and read_only true. For a fully local fixture, replace the merged Default, Engineer and System Operator roles with empty local roles and supply an explicit settings directory with profiles.memory.type = "memory" and a fresh default_data_path.

Start the released binary with --profile server --config-dir /absolute/path/to/project; supply TERRAPHIM_SETTINGS_PATH and TERRAPHIM_DATA_PATH for that isolated fixture. No --agent-data-dir is needed.

Actual MCP calls and outputs

build_autocomplete_index({"role":"project"}) reports 2 terms.

autocomplete_terms({"query":"Con","role":"project","limit":5}) returns:

Found 3 suggestions
concern
concern
risk

autocomplete_with_snippets({"query":"Con","role":"project","limit":5}) returns:

Found 2 suggestions
concern — Risk decision: approve a second supplier as the mitigation.
concern — Risk decision: approve a second supplier as the mitigation.

The repeated Concern entries are byte-identical. Kilo's saved tool records contain the same actual output; this is not a model-generated summary. In the same session, Risk and Concern searches correctly retrieve the same three Risk documents and an explicitly unknown role is refused.

Expected / acceptance

• Return each identical suggestion identity once; retain legitimately distinct terms such as Risk and Concern.
• Return one copy of an identical alias/source snippet, without losing a different source's snippet.
• Deduplicate before applying the requested result limit, so duplicate candidates do not consume it.
• Add real MCP stdio regressions using this authored synonyms:: fixture, covering index rebuild and role changes as well as the initial query.

This is a suggestion-quality defect. The released synonym-search and unknown-role fixes remain verified. Native Kilo UI discovery and marketplace admission are separate from this backend reproduction.