Problem#

The /agent directive prefix was too generic and clashed with unrelated strings (e.g. /agent-core-artefacts URLs). A more specific prefix /agentsde is needed, along with two new PR-scoped directives: discuss and fix-this.

Task / Link#

Closes #534

Changes#

• Regex update: hasAgentDirective(), extractDirectiveFromBody(), and extractDirectiveValue() now match /agentsde (primary) and /agent (legacy fallback) via (?:sde)? pattern
• PR review comments: handlePullRequestReviewComment() now accepts /agentsde directives without requiring an @mention
• New directives: discuss and fix-this added to ALLOWED_DIRECTIVES, VALID_DIRECTIVES, confirmation messages, and routing (discuss → reply_to_pr_comment, fix-this → address_review)
• Feedback strings: All hardcoded /agent <directive> strings updated to /agentsde <directive> across directive.service.ts and phase-router.service.ts
• Docs: AGENTS.md, plan-and-propose/SKILL.md, and internal-adapter comments updated to reference /agentsde

Notes#

• /agent remains fully supported as a backward-compatible legacy prefix — no breaking changes
• fix-this uses a hyphenated form (not two words) consistent with skip-quality-gate — single-token parsing
• E2E test updates (in agent-core-e2e) are out of scope for this PR per the plan assumptions

Testing#

• Unit tests added for /agentsde detection, backward-compat /agent, PR review comment directive without @mention, discuss/fix-this handlers, and new routing in resolvePhase()
• npm run test — 834 tests pass
• npm run lint — zero warnings