Module template 

Module: template

Template-mode support for in-place response documents. Parses structured patch blocks from agent responses and applies them to named component slots in the document, with boundary marker lifecycle management for CRDT-safe stream writes.

Spec

• parse_patches: Scans agent response text for <!-- patch:name -->...<!-- /patch:name --> blocks and returns a list of PatchBlock values plus any unmatched text (content outside patch blocks). Markers inside fenced code blocks (``` or ~~~) and inline code spans are ignored so examples in responses are never mis-parsed as real patches.
• apply_patches: Delegates to apply_patches_with_overrides with an empty override map. Applies parsed patches to matching <!-- agent:name --> components in the document.
• apply_patches_with_overrides: Core patch application pipeline:
  1. Pre-patch: strips all existing boundary markers, inserts a fresh boundary at the end of the exchange component (keyed to the file stem).
  2. Applies each patch using mode resolution: stream overrides > inline attr (patch= or mode=) > .agent-doc/components.toml > built-in defaults (exchange/findings default to append, all others to replace).
  3. For append mode, uses boundary-aware insertion when a boundary marker exists.
  4. Patches targeting missing component names are routed as overflow to exchange/output.
  5. Unmatched text and overflow are merged and appended to exchange/output (or an auto-created exchange component if none exists).
  6. Post-patch: if the boundary was consumed, re-inserts a fresh one at the end of exchange.
• reposition_boundary_to_end: Removes all boundaries and inserts a new one at the end of exchange. Used by the IPC write path to keep boundary position current.
• reposition_boundary_to_end_with_summary: Same, with optional human-readable suffix on the boundary ID (e.g. a0cfeb34:agent-doc).
• template_info: Reads a document file, resolves its template mode flag, and returns a serializable TemplateInfo with per-component name, resolved mode, content, and line number. Used by editor plugins for rendering.
• is_template_mode (test-only): Legacy helper to detect mode = "template" string.

Agentic Contracts

• parse_patches is pure and infallible for valid UTF-8; it returns Ok even for empty or patch-free responses.
• Patch markers inside fenced code blocks are never extracted as real patches. Agents may include example markers in code blocks without triggering unintended writes.
• Component patches are applied in reverse document order so earlier byte offsets remain valid throughout the operation.
• A boundary marker always exists at the end of exchange after apply_patches_with_overrides returns. Callers that perform incremental (CRDT/stream) writes may rely on this invariant.
• Missing-component patches never cause errors; content is silently routed to exchange/ output with a diagnostic written to stderr.
• Mode precedence is deterministic: stream override > inline attr (patch= > mode=) > components.toml (patch key > mode key) > built-in default. Callers can rely on this ordering when constructing overrides for stream mode.
• template_info reads the document from disk; callers must ensure the file is flushed before calling (especially in the IPC write path).

Evals

• parse_single_patch: single patch block → one PatchBlock, empty unmatched
• parse_multiple_patches: two sequential patch blocks → two PatchBlocks in order, empty unmatched
• parse_with_unmatched_content: text before and after patch block → unmatched contains both text segments
• parse_empty_response: empty string → zero patches, empty unmatched
• parse_no_patches: plain text with no markers → zero patches, full text in unmatched
• parse_patches_ignores_markers_in_fenced_code_block: agent:component markers inside ``` are preserved as content
• parse_patches_ignores_patch_markers_in_fenced_code_block: nested patch markers inside ``` are not parsed as patches
• parse_patches_ignores_markers_in_tilde_fence: patch markers inside ~~~ are ignored
• parse_patches_ignores_closing_marker_in_code_block: closing marker inside code block is skipped; real close is found
• parse_patches_normal_markers_still_work: sanity — two back-to-back patches parse correctly
• apply_patches_replace: patch to non-exchange component replaces existing content
• apply_patches_unmatched_creates_exchange: unmatched text auto-creates <!-- agent:exchange --> when absent
• apply_patches_unmatched_appends_to_existing_exchange: unmatched text appends to existing exchange; no duplicate component
• apply_patches_missing_component_routes_to_exchange: patch targeting unknown component name appears in exchange
• apply_patches_missing_component_creates_exchange: missing component + no exchange → auto-creates exchange with overflow
• inline_attr_mode_overrides_config: mode=replace on tag wins over components.toml append config
• inline_attr_mode_overrides_default: mode=replace on exchange wins over built-in append default
• no_inline_attr_falls_back_to_config: no inline attr → components.toml append config applies
• no_inline_attr_no_config_falls_back_to_default: no attr, no config → exchange defaults to append
• inline_patch_attr_overrides_config: patch=replace on tag wins over components.toml append config
• template_info_works: template-mode doc → TemplateInfo.template_mode = true, component list populated
• template_info_legacy_mode_works: response_mode: template frontmatter key recognized
• template_info_append_mode: non-template doc → template_mode = false, empty component list
• is_template_mode_detection: Some("template") → true; other strings and None → false
• (aspirational) apply_patches_boundary_invariant: after any apply_patches call with an exchange component, a boundary marker exists at end of exchange
• (aspirational) reposition_boundary_removes_stale: multiple stale boundaries are reduced to exactly one at end of exchange

Structs

ComponentInfo

Per-component info for plugin rendering.

PatchBlock

A parsed patch directive from an agent response.

TemplateInfo

Template info output for plugins.

Functions

apply_patches

Apply patch blocks to a document’s components.

apply_patches_with_overrides

Apply patches with per-component mode overrides (e.g., stream mode forces “replace” for cumulative buffers even on append-mode components like exchange).

parse_patches

Parse <!-- patch:name -->...<!-- /patch:name --> blocks from an agent response.

reposition_boundary_to_end

Reposition the boundary marker to the end of the exchange component.

reposition_boundary_to_end_with_summary

Reposition boundary with an optional human-readable summary suffix.

template_info

Get template info for a document (for plugin rendering).